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A course of study in household chemistry

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A course of study in household chemistry

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Content A COURSE OP STUDY IN HOUSEHOLD CHEMISTRY A Project Presented to the Faculty of the Department of Education The University of Southern California In Partial Fulfillment of the Requirements for the Degree Master of Science by Grace Louise. Lacouague June 1955 £ d * I-I H-5 This project report, written under the direction of the candidate’s adviser and approved by him, has been presented to and accepted by the faculty of the School of Education in partial fulfillment of the requirements for the degree of M aster of Science in Education. Adviser Dean TABLE OF CONTENTS CHAPTER PAGE PART I I. THE PROBLEM, HISTORY, PROCEDURE, AND ORGANIZATION . . . .............................. 2 The problem . . . . . . . . . . . . . . . . . 2 Statement of the problem . . . . . . . . . . 2 Importance of the study . . . . . . . . . . 3 History of the problem •••••••••.•• 3 The procedure • • k The organization..................... 5 II. THE REVIEW OF RELATED LITERATURE, SUMMARY AND CONCLUSIONS ................................ 6 The review of related literature ....... 6 Summarv and conclusions . . . . . . . . . . . 9 BIBLIOGRAPHY....................... ............ 11 PART II III. POINT OF VIEW AND USE OF MANUAL............. . 16 IV. UNIT I: THE CHEMISTRY OF THE COOKING OF F O O D .................................... * . 18 V. UNIT II: THE CHEMISTRY OF THE PRESERVATION OF FOOD ........................................ 39 VI. UNIT III: THE CHEMISTRY OF COOKING UTENSILS . . 52 VII. UNIT IV: THE CHEMISTRY OF TABLEWARE ........... 68 VIII. UNIT V: THE CHEMISTRY OF FABRICS ....... 91 CHAPTER PAGE ■IX. CHIT VI: THE CHEMISTRY OF STAIN REMOVING .... 115 X. OTIT VII: THE CHEMISTRY OF SANITATION IN THE HOME................ . .. i 128 XI. OTIT VIII: THE CHEMISTRY OF HOME DECORATIONS ... 155 APPENDIX...............................................170 PART I CHAPTER I THE PROBLEM, HISTORY, PROCEDURE, AND ORGANIZATION Chemistry, as it has been taught, has attracted only a small percentage of senior high school pupils. Many of these have enrolled in the course to satisfy college entrance requirements rather than to satisfy a genuine interest. The true importance of chemistry in daily living, particularly in the home or household, seems to be greatly neglected. The inquisitive mind of a high school student wants a simplified and complete answer. If the student enrolls in a general science or general chemistry class, he will learn numerous laws, formulas, and reactions through experiments. However, it has been proved that the student would rather have acquired the knowledge through actual problems related closely to his daily living. Daily living is centered in the home. Therefore, in order to give the student this opportunity of daily living realization, there is a need for a type of science course which caters particularly to the household. I. THE PROBLEM Statement of the problem. It was the purpose of this project to compile a course of study in first year household, chemistry to be taught to a class at the senior high school level in the Los Angeles City School District, A need exists, in the homemaking field, for a course of study in this subject. It was designed for a full year* Importance of the study. It is felt by some who are in the homemaking field that a course of study in household chemistry is needed in the Los Angeles City School System. At present there is no course of study available in the city school system which can be used as a guide to teach this ’ ’ practical1 ' course in order to meet the needs of the i students. Therefore, in order to teach household chemistry successfully, a course of study is needed to serve as a dependable guide. The compilation of this course of study is intended to satisfy this need. II. HISTORY OF THE PROBLEM If a student is interested in various types of re actions pertaining to his individual situation, the only course offered in the present system is either a general science, general chemistry, or a foods, clothing, or person al and family arts course in the homemaking field. Many students in the city school system do not plan to further their education past the high school level. Since public education attempts to achieve goals which are beneficial to the students1 desires and necessities, it Is onefs duty to take action upon the matter. An investigation determined that no course of study for the teaching of household chem istry has been approved or is available for use in the L 03 Angeles City School System. III. PBOCEDURE This course of study was written on the assumption that the students in this class were without training in previous science courses in school. Hox^ever, provisions were made.if the majority of the class had some chemistry background. The procedure followed was (1) to make a detailed study of the history of chemistry used in the home, which has to be used as reference material; (2) to include basic and essential chemistry principles In a modified form by using the problem approach; (3) to select meaningful prob lems related to the home as well as to chemistry and other sciences; (Ip) to perform and solve experiments on each problem; and (5) to draw up satisfying conclusions for each problem. Material used in compiling this course of study was taken from textbooks which contained students1 individual 1 *! ! experiences, and from the writer!s observations and exper iences • IV. ORGANIZATION This project was compiled so that it may be divided into two separate parts. The first part includes the state ment, importance, and need of the problem, a brief history of the problem, method of procedure, and organization of the' I project. The summary and conclusions follow the review of related literature. That is followed by an annotated bibliography. The second part is the course of study for the teaching of household chemistry, organized to be taught ' for a two semester period In the senior high school. CHAPTER II REVIEW-OF RELATED LITERATURE, SUMMARY AND CONCLUSIONS ..Much has been written in regard to the different phases of home chemistry. This material was found in un limited amounts from various sources* There is, however, a need for a single, comprehensive book covering household chemistry. Review of related literature. Many textbook authors strive unsuccessfully to attain the goal of writing a com plete and informative source book. Of all the textbooks available, the one written by Ahrens, Bush, and Easley^- seemed to be the most complete and useful. For chemistry related to the cooking of foods there was ample material. There were innumeral topics and various ideas for each. Since it was such a large topic, each part had to be considered separately. For this particular unit, the cook book, one of which is The Hew Joy of Cooking^, ^"Maurice R. Ahrens, Norris F. Bush, and Ray K. Easley, Living Chemistry (San Francisco: Ginn and Company, 19I+6), pp. 2 Irma S. Rombauer and Marion Rombauer Becker, The New Joy of Cooking (Indianapolis: Bobbs-Merrill Company, Inc., 195377 1013 pp. contributed many details that any other type of literature could not give. The Mew Joy of Cooking had excellent in sertions pertaining to all phases of food cookery chemistry. , Betty CrockerT s Picture Cook Book3 is another accepted authority. Each of these two sources had considerable information on the foods cooked by different methods. The first not only contained recipes but gave very specific in formation on cooking processes. The latter illustrated the results pictorially. Leavening agents, which are of great importance, were discussed in most types of literature used. A thorough explanation was found in Margaret E. Dodd’s Chemistry of the Household^- and supplemented by Garrett and associates.^ There are innumerable publications printed by the United States Department of Agriculture on all phases of food with a considerable emphasis on the preservation of food. This service is intended for the general public and xms explained in a simple and easy manner. Among many other ^General Mills, Incorporated, Betty Crocker ’ s Picture Cook Book (Mew York: McGraw-Hill Company, Incorporated, 1950 ), 1x6 3 pp. ^Margaret E* Dodd, Chemistry of the Household (Chica g o: American School of Home Economics, 19lll), pp. 8"9-ll|-3* 5 Alfred B. Garrett, Joseph Haskins, and Harry Sisler, Essentials of Chemistry (San Francisco: Ginn and Company, I95Tjy pp. 57^7?: . . A .publications available, that of Boyden Sparkes presents excellent, detailed information on the quick-freezing methods of preservation. Ahrens, Bush, and Easley*^ had a concise but thorough chapter on the chemistry of cooking utensils. Many manu facturing companies have printed material on the composition of their respective products as well. It seems as though the fact of utensil composition is seldom stressed enough. A i It was found that Helen Sprackling had a good reference on the chemistry of tableware. She included a complete guide on china, glass, and silver, as well as other miscellaneous items such as linens, which are used in table service. Evans9 and Wingate^® were both excellent sources for any phase of fabrics and clothing. Wingate, It was noted, had good chapters on testing and descriptions of various fabrics. Although these two references are fairly complete ^Boyden Sparkes, Zero Storage in Your Home (Garden City, Hew York: Doubleday, Doran and Co., 195577 213 pp. 7 Ahrens, Bush, and Easley, op. cit., pp. 3 3 k - 3 k 5 . O Helen Sprackling, Setting Your Table (New York: M. Barrows and Company, Incorporated, 19515', 213 PP* 9 'Mary Evans, Fundamentals of Clothing and Textiles (New York: Prentice-Hall, Inc., 1959), 632 pp. ^Isabel B. Wingate, Textile Fabrics (New York: Prentice-Hall, Inc., 1950), 6i |0 pp. in this field, the progress in processing textiles since 1950 has been so rapid that they did not have much material pertaining to the newer fabrics. Wingate and Evans are also good sources for stain removing. General Poods Corporation has published a pamphlet entitled How To Take Out Stains- * - which is very concise, complete, and comprehensive. Sanitation is a well documented topic. Besides the many textbooks and United States Department of Agriculture publications, there are informative materials published by municipal governments as well as by manufacturers whose pro ducts are used for sanitation purposes. In areas such as home decoration the supply of literature is relatively overabundant. Paint companies and distributors, contrac tors, appliance manufacturers and dealers, and numerous other sources, have made available many valuable publications. Summary and conclusions. In most cases, an inexhaus- tive supply of information can be secured, but from varied sources. As was stated in the beginning, the difficulty lies in the fact that all necessary Information is not con tained in any single publication. When the teacher prepares 11 How. To Take Out Stains (Consumer Service Depart ment, New York: General Poods Corporation, 1948). x°l to teach the subject, she must gather her materials from all; these sources* This may take months before she can actually begin to make her lesson plan. With this compilation of the related literature and all the various topics outlined in one course of study, it is hoped that the teacher can devote more of her time to her students and to furthering her own know ledge . BIBLIOGRAPHY I BIBLIOGRAPHY A. BOOKS Ahrens, Maurice, Norris P. Bush, and Ray K. Easley, Living Chemistry. San Francisco: Ginn and Company, 19lj-6. A rather complete textbook on everyday chemistry with a unit on household chemistry. Bailey, E. H. S., A^ Textbook of Sanitary and Applied Chemistry. San Francisco: The Macmillan Company, (n. d.). College text, based on course in general chemistry. Contains good information of preservation of foods. Bogert, L. Jean, M. D., Nutrition and Physical Fitness. Fifth edition. Philadelphia: ¥. B. Saunders Co., 1951. A textbook on nutrition with an excellent portion on dietary habits and food Intake. j 1 Dodd, Margaret E., Chemistry of the Household. Chicago: ! American School of Home Economics^ 19ll+* Excellent portion on cleaning, laundry, baking powder, and soap making along with other fields. The book is very simply written. Evans, Mary, Fundamentals of Clothing and Textiles. New York: Prentice-Hall, Inc., l9l£9. Has an excellent chapter on new fabrics. Garrett, Alfred Benjamin, Joseph Frederic Haskins, and Harry Hall Sisler, Essentials of Chemistry. San Francisco: Ginn and Company, 1951. Gives a small but-up-to-date review of chemistry of today which is found in the home. Noller, Carl R., Chemistry.of Organic Compounds. Philadel phia: ¥. B. Saunders Company, 195>1. ~ Excellent book on detergent consumption figures. Rombauer, Irma S., and Marion Rombauer Becker, The New Joy of Cooking. Ninth edition. Indianapolis: Bobbs- Merr ill C omp any, Inc., 1953. A cook book with excellent notations regarding any questions that might arise from a cook. It is a very . complete._one.,_ very, excellent, .source for.most, anything.. Snell, John Ferguson, Elementary Household Chemistry. San Francisco: The Macmillan Company, 1937* Adapted to college use. Includes iron rust, soap, cleaning, fabrics, bleaching, etc. The book could be better. Sparkes, Boyden, Zero Storage in Your Home. First edition. Garden City, New York: Doubleday, Doran and Company, Inc., 19i{i|-* This has an excellent chapter on the history of food freezers. It is also good as a reference book for freezing foods because of its tables, charts, etc. Sprackling, Helen, Setting Your Table. Second edition. New^ York: M. Barrox<rs and Company, Inc., 1951* 1 Has a rather complete discussion on various items used in table service such as linens, china, glassware, silverware, and the like. Weed, Henry T., Chemistry in the Home. Cincinnati: American Book Company, 1918. For students xtfho elect chemistry early in high schooll course. Includes baking pox^ders, soaps, food preserva tives, textiles, laundry, and the like. Williams, W. Mattieu, Chemistry of Cookery. New York: D. Appleton and Oompany, 1913* This is written for the unlearned but intelligent reader centered on foods. It is very detailed. Wingate, Isabel B., Textile Fabrics. Third edition. New York: Prentice-Hall, Incorporated, 1950* An excellent book regarding anything which pertains to textiles. B. PUBLICATIONS.OF - OTHER -ORGANIZATIONS How To Take Out Stains. Consumer Service Department, New York: General Foods Corporation, 19ij.8. An excellent little pamphlet on the removing of stains. Betty Crocker1s Picture Cook Book. New York: General Mills, Inc., and McGraw-Hill Company, Inc., 1950* The recipes found in this book are very good, the results shown pictorially. C. UNPUBLISHED MATERIALS Borg, Milton R., nA Course in Everyday Chemistry.” Unpublished Master’s Project, the Univeristy of South ern California, Los Angeles, 1952* A project designed to establish the importance of chemistry to everyone. There are various formulas and directions for ”how to make it yourself” Items. Very useful* PART II A COURSE OF STUDY nr HOUSEHOLD CHEMISTRY POINT OF VIEW This course of study was compiled with the under standing that it would be taught to students undertaking such a field of study. It is intended as a complementary course to the general chemistry course which is taught in senior high school. Students would not be required to take this course, although it would be to their advantage to enroll. The student, himself, determines the topic or topics about which he would like to learn more. His immediate environment should be investigated by the teacher and the studentTs study should be directed toward the betterment of | that envir onraent. Primarily, the course should be taught as a subject which is to meet the immediate needs of the pupils. While doing this, the student should enjoy it and have the proper attitude. He should become aware that he lives very closely to the chemical world. Perhaps this might awaken his inter est in broader scientific knowledge. With a successful completion of this course of study, the student should become a better citizen In his community. USE OP COURSE OP STUDY This course of study is constructed in such a way that the teacher should find it most useful as a guide and reference tool. It is in outline form, with paragraphs in serted wherever it was necessary to more fully explain the topic. It should be understood that such an outline could not be complete In any respect. The teacher should present much more additional material than what is found In this course of study. The exercises found at the end of each problem are only sample questions. The teacher must compile his own examination, using his particular group as a guide, rather < than use the questions which appear here. Likewise, the suggestions or extra problems should not necessarily be given to individual pupils unless they are capable of doing them and If such a problem would be worthwhile for that student. An exercise or test for each unit Is found In the ■ appendix. However, the students should be the determining factor for such group tests. No suggested time has been mentioned for each unit, although the course is planned to cover two semesters. Each class should set the pace which It will follow. Some units, because of their areas for expansion, will take a greater amount of time than others. UNIT I THE CHEMISTRY OF THE COOKING OF FOOD Cooking today Is a highly specialized art, comprising many procedures which the x<*ell-inf ormed housewife or the chef can use to gratify hungry appetites. Today one may bake, boil, broil, stew, fry, steam, or roast food, but one ■ should know the results of each kind of cooking if the food Is to be healthfully served. We must not forget that foods are chemical substances, and that heat in any form hastens the speed with which chemical reactions occur. Some of the effects of cooking are chemical changes, and some are merely, physical, and the well-informed, person understands what they are. Purposes: The purposes to be achieved in this unit are the following: 1 . To understand the reasons for cooking foods. 2. To understand what part chemistry plays in the cooking of foods. 3. To improve cooking techniques through the use of chemical knowledge. ii. To learn hox^r to cook foods so that the food values are not destroyed. 5. To learn related vocabulary. 19 Problems: The problems to be solved in this unit are: 1. Why do we cook food? 2. How are foods affected by the different methods of cooking? a* What chemical changes take place when food is cooked? b. What are the advantages of the various ways of cooking food? c. What precautions should we observe in cooking food so that the nutritive values are retain ed? 3. What makes jellies jell? L f . , How are leavening agents used in baking? Word list: Oolloid: a gelatinous or other substance which when dissolved in a liquid will not diffuse readily through vegetable or animal membranes. Uutrient: that which nourishes. Palatability: agreeable to the taste. Problem I: Why do we cook food? A. The cooking of food is beneficial to health. B. Cooking destroys germs. 20 C. Cooking makes food more appetizing. * D. Cooking improves digestibility. E. Cooking provides a wider variety of foods. P. Cooking should be done carefully. Exercises: 1. List five reasons for cooking food. Justify each reason you name. 2. What foods are most likely to be overcooked? 3. What foods are best for our health when they are eaten in the uncooked state? Why? I j . . What foods should be thoroughly cooked? Why? i Problem II: How are foods affected-by the different methods' of cooking? A. Vegetable cookery. 1. Cooking of vegetables tends to remove or destroy valuable food nutrients. 2. Vegetables contain carbohydrates, proteins, vitamins, cellulose, minerals, and varying small amounts of fat. a) Carbohydrates: These 0001x1 ? in vegetables in the form of starch; cooking swells the starch granules, causing them to burst. b) Proteins: Some of the proteins are soluble in water and therefore dissolve in the water in which the vegetables are cooked; most proteins are coagulated by heat either in the cells of the vegetable or in the water in ' which they are dissolved* c) Vitamins: Vegetables are one’s principal source of vitamins and one should be particu larly careful in cooking them so that as little as possible of their vitamin content is destroyed. (1) Vitamin A is a fat-soluble vitamin; most vegetables are cooked in water and since* the heat does not decompose it, one does' not have to be especially careful in cooking vegetables containing this vitamin. (2) Vitamin B is a water-soluble vitamin but. boiling water does not destroy it; this vitamin will not be lost unless the cooking water is thrown away. (3) Vitamin C is an easily oxidized vitamin; since oxidation is increased by raising the temperature and by prolonged heat ing, it is evident that the cooking of 22 vegetables will destroy this important vitamin. (Ip) Vitamin D is fat-soluble; it is not found in many vegetables so one does not have to be concerned about the loss of this vitamin in the cooking of vege tables. (5) Vitamin E is not destroyed by cooking; it is distributed so well among vege tables and cereals that one rarely suffers from a deficiency of it. (6) Vitamin G is a water-soluble vitamin; j boiling water does not destroy it so it ■ will not be lost unless thrown away. d) Minerals: Since vegetables are one1 s princi pal source of minerals, one should make every effort to conserve the minerals in the cook ing process; the valuable minerals in vege tables which are eaten occur mostly as soluble inorganic salts. e) Cellulose: This is the roughage in vegeta bles; it is the husks, stems, and leaves of vegetables which are not affected nor de stroyed by cooking regardless of what cooking method is used* 3* Rules for cooking vegetables: the chemistry of cooking vegetables can be summarized as follows: a) Cook them in as little water as possible* b) Serve the cooking water with them. c) Keep the vegetables covered. d) Remember that mineral content and vitamins B, C, and G- are most easily destroyed or lost by cooking. e) To preserve palatability, flavor, and tex ture, undercook them rather than overcook them. Meat cookery. 1. Meat is an important food for protein content; in meat cookery one should be most concerned with the changes that take place in the protein which meats contain. 2. In the cooking of all protein-containing foods, heating to too great a degree coagulates the pro tein which makes it less soluble and consequently less easily digested. By abiding to this princi ple, meats, as well as eggs, milk, and vegetables which contain protein will then be most nutri tious . I I 3. The composition of meat is an important factor for a more complete knowledge of its results to cooking. Meat tissue contains muscle fibers, connective tissue, and fat tissue in addition to vitamins, minerals, and some carbohydrates. a) Muscle fiber is a protein, rod-like in struc ture and is held together by connective tis sue. The muscle tissue contains solutions of salts, vitamins in small quantities, and sev eral proteins, such as globulin, albumin, and, in the red meats, hemoglobin. High heat; I \ tends to coagulate these proteins, making them less soluble and less digestible* b) Connective tissue is more popularly known as tendons; it serves similar to what cellulose does for plants— it is the supporting tissue. This tissue contains a protein-like substance called collagen which is swelled by heating and is thus made more soluble and consequent ly more digestible* Dilute acids affect collagen similarly, and this accounts for the fact that tough meat can be made more tender by adding a small amount of vinegar. If meat contains much collagen, it should first be pounded or soaked in vinegar before cooking is attempted. c) Other nutrients, such as vitamins, minerals, ; and some carbohydrates are found in meat. These are found in a rather small quantity so one need not be too concerned with the loss of these from cooked animal foods. There are basically only two methods of cooking meat, namely, that of moist heat and that of dry , j heat. a) Moist heat is needed when cooking the less tender cut of meat. This type of meat con- ! tains more connective tissue. Connective tissue is softened by water. One desires this softness so it should be cooked by moist heat. However, the soluble substances in the meat, such as minerals, vitamins, and soluble proteins, are extracted from the meat into the water. The longer the cooking pro cess, the greater the extraction. This type of cooking is called either braising, stew ing, frying, boiling or simmering. b) Dry heat cooking is the process of either roasting, broiling, or pan broiling. Tender cuts may be cooked by dry heat because they contain very little collagen, or connective tissue. Tenderizing is a process used in treating less tender cuts of meat. The general process used for tenderizing hams, for example, is this: potassium nitrate, potassium nitrite, and sodium chloride solutions are injected into the hams by forcing them under pressure into the main artery which enters the ham. The solutions penetrate every fiber of the ham through the subdividing arteries and capillaries. The solution breaks doiArn the collagen and thus the ham need not be subjected to so much heat to make it tender. Rules that are considered most important for cooking meat are: a) Roasting (1 ) Leave meat at room temperature for at least one half hour before roasting. (2) Place meat on pan, fat side up in a preheated oven. (3 ) Do not decrease or increase heat at any time. (ij.) Do not cook at too high a temperature. 27 C5) Length of time varies for each piece of 1 meat, b) Broiling (1) Do not place salt on meat before cook ing, (2) Preheat broiler to 35>0° P, (3) Have meat at room temperature. (k) Place meat about three inches from broiling unit. (5) Broiling time depends upon thickness of the meat and the degree of doneness desired. | c) Braising 1 (1) Brown meat in a little fat. (2) Place the meat in a heavy kettle. (3) Add enough boiling water or stock to cover the bottom of the pot. Cover tightly. (k) Simmer the meat on top of the stove until it is tender. (5 ) Phe. time required will.depend on the size and cut of the meat. d) Stewing (1) Cut meat into cubes. (2) Brown lightly if desired. ! (3) Place in hot liquid and simmer until tender. e) Pan-broiling (1) Place meat in hot skillet. (2) Add no water and no lid; sear quickly and as fat melts, remove immediately. (3) Season and. serve. Exercises: 1. What food nutrients are found in vegetables? 2. How should vegetables be .cooked to preserve the nutrients and yet be palatable? 1 3. What nutrients are most likely to be lost when vegetables are cooked? Why? ! { . , What difficulties are likely to be encountered in cooking vegetables which contain considerable protein? 5. Make a list of the vitamins found in foods. Des cribe each one from three points of view: its properties, its sources, and the readiness with which it is lost in cooking. 6 . What precautions should be observed in the cook ing of vegetables to preserve their mineral con tent? _Explain the “waterless1 1 method of. cooking . vegetables. 7 . "Why should we include meat in our diet? 8. What substances are found in lean meat? 9. When meat is cooked, what happens to the fat which it contains? 10. How should tough meat be prepared for cooking? Why? 11. List the various ways of cooking meat and de scribe the effect of each method on the meat. Problem III: What makes jellies jell? A. A colloidal solution results when a polysaccharide, pectin, is concentrated in the presence of sugar. When the solution cools, it forms a jellied struc ture. B. In a true solution the dissolved particles are so finely divided that they are actually scattered as molecules. C. The reason for a precipitation of a dissolved sub stance is that the molecules of the substance band together into such large particles that they cannot remain in solution. D. The size of the particles that make a colloidal solu tion is between that of the particles of a true solu- tic11, that of the particles of a precipitate. 301 i E. Colloidal solutions cannot be filtered, and many times they exhibit a jelly-like consistency. P. Pruit jelly is made in the manner described below. 1. As fruit grows, a chemical called protopectin is produced. 2. When the fruit begins to ripen, the protopectin is changed to pectin. When the fruit becomes ripe, the pectin is changed to pectic acid. 3# Pectin is the only chemical which, when concen trated with fruit juice and sugar, will produce a colloidal solution and result in jelly. I } . . Success in jelly-making will be much more likely , if slightly under ripe fruit is used. G. Commercial jelly is made in the manner described below. 1. This jelly is a product extracted from apples and citrus fruits. 2. This is superior to those jellies produced by the prolonged boiling of fruit juices and sugar be cause of the retention of the fruit flavors. It also requires less sugar. H. Gelatin (animal jelly) is used in jelly cookery. 1. This is obtained from the bones of animals. When it is dissolved with sugar in hot water, a colloidal solution forms * This colloidal solu- ! tion produces jelly on cooling. 2. When gelatin is mixed with sugar and fruit flavoring a very palatable food is obtained. It is sold under several well-known trade names. Exercises: 1. Define a colloidal solution. What is the differ ence between a true solution and a colloidal solution? 2. Explain the formation of jelly when fruit juices i are cooked with sugar. 3. What is pectin? How is it produced in fruits? ; l±. What is the difference between commercial gelatin and jelly? Problem IV; How are leavening agents used in baking? A. The tise of leavening agents in making bread and-cake are as follows: 1. Bread and cake made with a leavening agent is light and therefore easily chewed. 2. Since foods baked with leavening agents are full of holes, the digestive juices come in contact with the food more readily and digestion is greatly facilitated. 32| 3* Bread and cake made with, such agents are much more palatable and appetizing. B. Kinds of leavening agents are listed as follows: 1. There are three general methods used in leavening of bread. a) Shipping air directly into it. This is used to a small extent. b) Use of yeast is very popular. (1) Yeast is a microscopic plant, no species being large enough to be seen with the naked eye. Countless millions of these small plants are pressed together to make the common yeast cake. (2) If a bit of yeast cake is mixed with a little water, these little plants in crease in number very rapidly. It is in the process of growth that the gas carbon dioxide is formed. (3 ) Yeast plants all require sugar for food, moisture, and a warm, even temperature to bring about reproduction and growth. (I 4. ) Bread dough is a good medium for this groxrfch, since it contains some sugar which has been mixed with the flour. 33 (a) Some of the starch of the flour is also converted, into sugar by the action of enzymes, or organic catalysts. (b) When the sugar is acted upon by the yeast, the two products alcohol and carbon dioxide gas are formed. (c) As the gas is formed, the small bubbles are trapped in the dough, causing the increase in volume. (d) Baking causes the dough to solidify around the bubbles, thus producing light bread. (e) The heat drives off the alcohol which has formed in the reaction. Use of chemicals is very popular. (1) Baking soda as a leavening agent. (a) Baking soda, or sodium bicarbonate, has the formula HaHCO^ and is sold by grocers as bicarbonate of soda. (b) Baking soda will liberate carbon dioxide when heated. The products other than carbon dioxide are sodium carbonate (washing soda) and 3k water, (c) Baking soda in biscuits is not un common, One thoroughly mixes soda with flour and then mixes with shortening and sour milk. When biscuits are placed in the oven, the heat causes the lactic acid of the milk to react with the baking soda to produce carbon dioxide. The liberation of this gas causes the biscuits to be leavened. ; I (2) Baking powder as a leavening agent. j (a) Baking powders were first put on the market around 1850 because chemists realized the difficulty of mixing correct amounts of baking soda and sour milk to be used as leavening agents every time a leavening agent was needed. (b) All baking powder contains three ingredients: i) Baking soda, which produces the carbon dioxide, ii) A dry acid-forming substance, or acid salt, which, forms an acid by hydrolysis, iii) Starch, which helps to keep the mixture dry so that the other two ingredients will not react : with each other. There are several different types i of baking powders since several acid salts are available, i) Alum baking powders. This type contains sodium aluminum sul- i fate as the acid ingredient which hydrolyzes in water to form sulfuric acid. This acid reacts with the sodium bicar bonate to form carbon dioxide which produces the leavening action. Powders containing sodium aluminum sulfate are often designated as SAS powders and react slowly at room tem peratures, ii) Phosphate baking powders. The ■ acid ingredient of this type of 36 baking powder is soluble cal- , cium acid phosphate. This form of calcium acid phosphate is obtained from bone ash treated with sulfuric acid. The rate of reaction in this type of powder is rapid because of the readily available hydrogen ions; in the acid salt. Batters and doughs containing this salt must be caked quickly, since the carbon dioxide is given off soon after the water or milk is' added. iii) Tartrate baking powders. This type of baking powder contains cream of tartar, or potassium acid tartrate and was the first substance added to baking soda to make baking powder. Since it is an acid salt, it reacts rapidly, and baking must take place rather soon after mixing, iv) Double-acting baking powders. Very often a manufacturer uses both calcium acid phosphate and sodium aluminum-sulfate as the acid-forming ingredients in his particular brand of baking pow der. The advantage of this kind of baking powder is that the first acid ingredient be gins to act very soon after being mixed with the dough or batter, whereas the second re- : acts more slowly, during the 1 baking. Exercises: 1. What is a leavening agent? Describe three different leavening agents. 2. Why is bread which has been made by the use of leavening agents called light bread? . 3. How is yeast produced? What is yeast? L j _ . What are the kinds of baking powder which are commonly sold? What is the composition of each? 5. What are the differences between baking soda and baking powder? . __6 _ What _ is_ a double -acting baking powder ? 7. Consult your mother about the kind of baking powder that she uses and find out why she prefers that particular kind. Extra problems: 1. Write to your state home economics department or to the Bureau of Home Economics in the Federal Department of Agriculture, and ask for informa tion about the effect of altitude on baking and about the changes necessary in a recipe to be used at a high altitude, 2. Examine the labels on bottles of tomato catchup to see how many brands contain benzoate of soda, 3 . Look often on the labels of baking-powder cans to see what the ingredients of different brands UNIT II THE CHEMISTRY OP THE PRESERVATION OP FOOD Most people are acquainted with the fact that most food will spoil after It has been exposed to the air for some time. This spoilage Is due to the growth of micro organisms in the food. In many cases, the chemical decay produced by these microorganisms is harmless; hut in other cases, the decayed food contains dangerous toxins which are very harmful to the body. Purposes: The purposes to be achieved In this unit are the following: 1. To learn the necessity of preserving food. 2. To become acquainted with several methods of preserving food, and the processes used In each method. 3. To learn the values of home preservation as x^ell as commercial food preservation. Problems: The problems to be solved in this unit are: 1. Why is It necessary to preserve food? 2. How is food preserved? Word list: Microorganisms: microscopic (animal or vegetable) or gam sm. Preservation: to prepare so as to resist decomposi tion or fermentation* Putrefy: cause to rot or decay with an offensive odor* Toxin: synonymous to poison. Problem I: Why is it necessary to preserve food? A. The processes used in the preservation of food re tard spoilage, and consequently remove a potential danger to the body, B. Through the process of preservation, it is possible for the foods of all nations and all regions to be made available to everyone, wherever he may live, C, Fresh fruits and vegetables and other perishable foods can be grown in California, shipped to the markets in Hew York City, and sold to consumers in a condition comparable to the condition in which they are offered in California!s local markets. D, The preservation of food makes possible more reason ably priced food, particularly during the winter. Large quantities of foods which have been preserved by cold storage or other means can be sold at lower prices than would be possible if the same food were available in quantities natural to the season.. E. The restriction of the consumption of foods to their growing season has been forever removed by food preservation. Exercises: 1, What are the advantages of preserving food? 2. List the advantages according to your idea of importance. Problem II: How is food preserved? There are.many ways of preserving food. Drying, chemical preservation, refrigeration, quick freezing, and heat penetration are the most important processes. A. Drying. 1. Pood preservation by drying has been practiced since ancient times. This practice is still fo!3.owed, but today the drying of food has be come a commercial industry in which controlled conditions make possible mass production. 2 . The preservation of food by drying is based upon the removal of water. When water is removed from food, the possibility of the groitfth of micro organisms is lessened, because water is necessary for their growth. 3. The amount of water which needs to be evaporated I f . 2 depends on the amount of sugar in the food. The greater the amount of sugar, the less the drying that is necessary. This is due to the fact that a high concentration of sugar will aid in the preservation of food. I } . . Many families, especially in rural areas, have resorted to dried foods for economical living. 5. Many new processes have been discovered, and food of excellent quality has been preserved by drying. 6. It is, however, generally recognized that dried foods are not as palatable as fresh or canned foods; and there is evidence to prove that dried foods lose some of their vitamin content. B. Chemical preservation. 1. Many chemicals have the property of destroying or checking the growth of microorganisms. Some of these chemicals are used in the preservation of foods, others might be harmful to the body if used, and are prohibited by the pure-food laws. 2. Chemicals are often used to supplement another preservative. a) Sodium benzoate is added to foods for its additional preservative value. b) Sulfur dioxide is frequently used in fruits i I which are being preserved by drying. It prevents darkening of fruits. When either of these two chemicals is used, the United States government requires that It be de clared on the label of the food If the food is to be shipped in interstate commerce. A harmless food preservative Is common table | salt. a) Foods preserved with salt are fully protected against the growth of microorganisms. b) A part of the preservative action of salt Is , due to a principle known as osmosis. (1 ) Osmosis takes place when water passes through a cell membrane Into a solution of higher concentration. (2) Food is preserved because it has been partially dried through this reaction of osmosis. (3) Many meats are preserved with salt. c) The preservative action of salt or water glass in the case of eggs is due to their ability to keep air and microorganisms from passing through the porous shell and causing putrefaction. Smoke, spices, and formaldehyde are other sub stances which are used in food preservation. a) Smoke: this preserving action is due to the ' presence of organic chemicals called phenols. Pish and meats such as bacon and ham are often smoked to ensure their preservation. b) Spices: this preserving action contains organic acid forming compounds lihich inhibit the growth of germs* c) Formaldehyde: this preserving chemical is very dangerous. It is sometimes used to preserve milk although many municipalities have laws against its use because it is a strong toxin. The most commonly used chemical preservative is sugar. a) It is effective against the growth of all microorganisms except molds. b) Its preservative action is due to its absorp tion of water from the microorganisms. The improper use of chemical preservatives, with its accompanying dangers, Is due to antiquated laws and unintelligent consumers* To change such conditions will necessitate the education of the consumer, who in turn will demand protective laws. a) Some unscrupulous meat vendors sell ,!dyna- raitedt f Hamburger (reddening of the meat) very cheap to attract customers to their stores. Though this practice is unlawful in most states and one which should be reported to health authorities, it is not uncommon. b) Milk is one of the foods that is most readily contaminated with germs, especially if it is not properly handled. If it is properly cared, for and pasteurized., it requires no added preservative. Many unscrupulous dair ies, however, which do not care to go to the expense involved in the proper handling of milk, will compensate for poor sanitation and delay in delivery by using the preservative formaldehyde. Such a practice should be out- laifed by discriminating consumers. C. Refrigeration. 1. Refrigeration is a convenient and widely used method of preserving foods. 2. The preserving action of refrigeration is due to the fact that low temperatures check the growth of microorganisms and, in some cases, destroy them. 3# Cooked or uncooked food can be kept for a much longer period of time in a refrigerator. i | . . The convenience of home refrigeration and the saving of food made possible thereby have become very important to the modern household* 5, Industry uses refrigeration on a larger scale than that of the household. Meat products and fruits and vegetables are shipped to all parts of the world In refrigerator cars, trucks, and ships. By this method It is possible not only to open new markets for food products produced in many localities, but also to supplement the diet with fresh food, regardless of the season of the year. D. Quick freezing. 1, In very recent years it has been discovered that when food Is frozen quickly at a temperature of -Lj.O° F, the crystals formed are very small and do not pierce or destroy the cell walls of the food. 2. Food frozen by this method can be preserved inde finitely and, when thawed, retains its original freshness. Strawberries preserved in this way are as good as when they were first picked. 3. The quick-freezing method is growing fast. Foods processed in this inray are used extensively by hotels and restaurants, and their use in private households is spreading rapidly. E* Canning (heat penetration). 1. The principle' involved in canning is that of killing the germs through heat penetration and then sealing the can or jar, thus preventing the entrance of any new germs from the air. a) Commercially, this is done by placing the food in tin cans, heating for a short time to- sterilize the air, sealing, and then process ing, or heating, to cook the food. b) In the home, this is achieved by the open- kettle method, cold-pack, or cook-in-can method. 2. It is known that acid-containing fruits and vege tables are more easily canned than such vege tables as corn, peas, and beans. The reason for this is that food-spoiling germs do not thrive well in an acid medium. 3. To secure the higher temperatures necessary, it p] I is best to use a pressure cooker, since an in crease in pressure increases the temperature within the cooker. 1^. Long cooking tends to destroy the vitamins pre sent, especially vitamin C, and to darken the color of the food, as well as impair the flavor. For this reason, the careful housewife or canner will heat the food only as hot as is necessary and for as short a period of time as is required. 5# One of the reasons why the average life span of man has been greatly increased is that today he is assured of not only an abundance of food through canning, but also a greater variety, which ensures a more healthful diet the year round. 6 . Home canning is useful for housewives who have the time, the equipment, and an abundance of fruits and vegetables. 7. Open-kettle canning is apt to destroy vitamins C because the food is exposed to the oxygen of the air. This method is therefore not advised except for foods of a high acid content, such as toma toes, apricots, and peaches. The acid medium preserves vitamin C in these foods. 1 + 9 o. The higher temperatures and presealed cans em- ! ployed by commercial canners ensure better canned* vegetables than can be obtained by the usual home methods. In the commercial method more heat penetrates the inner portions of the food, and the higher temperature kills heat-resisting germs; that might not be destroyed by home canning methods. 1 i 9. There is no danger of metallic poisoning from the, present day machine-made, lacquer-lined, machine-. I sealed eans used by modern commercial canners. i 10. Commercially canned food, as well as home-canned | food, may be left in an opened can without any j more fear of spoilage than if it were immediately emptied into another container. In fact, there is less danger of spoilage because the can is sterile, whereas the other container probably is not. 11. Pood canned by either method, if made absolutely sterile and sealed airtight, will be preserved indefinitely. 12. Tin cans should not be jammed and dented. If s . can bulges at either end, this indicates that there are gases inside it caused by putrefaction. 5o I i Such a can should be discarded without being opened. 13, Home-canned vegetables may be a source of the disease known as botulism. This disease is pro duced by a spore-bearing kind of bacteria which resists heat under 212° F. Commercial .canners can their vegetables at temperatures higher than 212° and therefore ensure the destruction of the s e germs. Exercises: 1. What are the advantages of preserving food? 2. What part does chemistry play in the preservation' of food? What chemicals are used? 3. Briefly describe the various methods of food preservation. ! } _ . Explain how hams are tenderized. 5. Consult a meat-packer or butcher in your locality on the subject of the making of wieners, or , f hot dogs”, and try to determine the origin of the term. 6. What control over food preservation should the government exercise in order to safeguard health? 7. Why does refrigeration preserve food? 8. What difference exists between quick-frozen food _ and that which is frozen by ordinary methods? 9. How does canning preserve food? 10. What foods are easily canned? Why? 11. What foods are difficult to can? Why? 12. Which are better, commercially canned foods or home-canned foods? Why? Extra problems; 1. How are foods adulterated? 2. How is dried beef prepared? Is it as nutritious as fresh beef? 3. Make an investigation of the milk-inspection department of your city or state. Determine how prevalent the use of formaldehyde is as a preservative. I 4. . Obtain information about the quick-freezing process of preserving foods, and make a report to the class. 5. Make a survey of the meat markets in your local ity to determine how prevalent the practice is of u si ng T t dynami t e. n 6 . Write to the bureau of health in your state and ask about the rules and regulations governing the selling of fresh meat. UNIT III THE CHEMISTRY OF COOKING UTENSILS The kitchen In one's home Is more or less a modern chemical laboratory. As one has learned, foods one prepares and eats are really chemicals. The cooking utensils such as the pots and pans are also made of chemicals. It is very necessary that the housewife should select vessels made of the proper materials with which to prepare the daily meals. Probably more change has been made In the kitchen by scien tific discoveries than in all the rest of the house. Kitchen equipment Is made from the more common materials such as copper, glass, clay, aluminum, iron, and tin. The use of these materials and appliances, which have been pro vided through scientific research, has removed much of the drudgery from the tasks of the housewife* Purposes: The purposes to be achieved in this unit are the following: 1. To gain a knowledge of the materials of which cooking utensils are made. 2* To learn how the materials of a cooking utensil affect cooking. 3* To recognize the dangers resulting from the use of different types of cooking-utensil materials. i|- To learn how to buy cooking utensils wisely. Problem: The problem to be solved in this unit is: What are the important facts that you should know about cooking utensils? The following questions will be considered as aluminum, tin, iron, copper, glass, and clay utensils are discussed: 1. How is this type of utensil made? 2. What are the advantages and disadvantages of this type? 3. What dangers accompany the use of this type? L { _ . How should this type of utensil be_ cared for? 5. What factors should be considered when purchasing utensils of this type? Word list: Corrode: to eat away gradually, as if by gnawing, especially by chemical action. Malleable: capable of being extended or shaped by hammering or by pressure with rollers. Problem: What are the important facts that you should know about cooking utensils? A. Aluminum. 1. . Heavy utensils such as pots and skillets are cast from_molten aluminum metal. Other utensils .are . 5 l | j pounded into shape from sheet aluminum to form a utensil, since aluminum is very malleable. 2. The advantages of aluminum cooking utensils are plentiful. a) Aluminum conducts heat very readily. b) It is low in density. c) It polishes with a high luster. d) Aluminum corrodes rather easil.y, but the corrosive film acts as a protective coat against further corrosion. e) Aluminum utensils may be purchased at rather reasonable prices. 3. The disadvantages of aluminum cooking utensils are not too plentiful. a) Some of the aluminum dissolves in the cooking food, it has been said, and Is a poison to the body. Extensive studies by unbiased scientists have not disclosed this fact* However, there are some foods which should not be cooked In aluminum utensils. b) Aluminum is a rather active metal and Is readily acted upon by most acids. Conse quently, foods such as tomatoes and fruits xAalch contain acids, should never be cooked 55 in aluminum utensils. It may produce an undesired flavor and may cause the utensil to pit more readily. c) Aluminum is acted upon by alkaline foods and bases whose action usually cause discolora tion and pitting. d) Baking soda, washing soda, or lye should never be placed In aluminum utensils. I | - . The care of aluminum utensils is important. a) Aluminum pans and kettles may be bought in various weights. b) Since aluminum is a soft metal, it is very malleable and may be dented easily. Care must be taken with thin aluminum not to dent it. c) Aluminum Is easily scratched and cut, and often a pan is ruined by cutting with a knife or some other object. d) 'Aluminum has a low melting point so there is some danger that holes will be burned through, the bottom of thin pans if all the water is allowed to evaporate from the cooking foods. e) All aluminumware has a tendency to pit be cause of the activity of aluminum. f ) Aluminum sometimes displaces small amounts of other metals in foods, causing an objection able discoloration of the utensil. There are cleaning materials on the market containing sodium silicate in colloidal form, which will prevent some of the pitting and discolora tion, g) Heavy rolled aluminum or cast aluminum makes the best cooking utensils, A tin can contains very little tin. In reality, it is an iron can covered with a very thin coat ing of tin. The advantages of tin are: a) Tin is relatively low in the displacement series and consequently is not acted upon chemically by weak or dilute acids. b) It has the property of adhering to the clean surface of many other metals. c) Tin plate can be pressed, cut, or crimped into various shapes. d) It retains Its shiny luster. e) It is Inexpensive. The disadvantages of tin are: a) Tin is mined in the faraway Malay States, the Dutch East Indies, and in Bolivia. Since none is produced in the United States, a can, cup, or plate made entirely of tin would be expensive. b) Extreme care should be used to avoid scratch ing through the tin covering, as the iron will begin to rust as soon as It is exposed to air and moisture. The manufacture of a tin can Is intriguing. The steps are as follows: a) Iron is plated with tin by first Hpickling” a sheet of Iron in dilute sulfuric acid. This removes any iron oxide and leaves the surface perfectly clean. b) The clean sheet iron Is then Immediately Immersed In molten tin. c) As the sheet iron is withdrawn from the vat, a thin coating of tin adheres to the surface of the iron, thus producing tin plate. This tin-plated iron is the material of which are made the millions of tin cans that are used daily to preserve a large percentage of the food that the nation consumes. 58 ! 5 , Tin plate finds some use in the kitchenware through pie and cake pans, C, Iron. 1. In the pioneer kitchen, many iron utensils could be found because it is rugged and sturdy. The replacement of utensils took a long time and was expensive. 2. There are still a number of iron utensils in many: i kitchens. Most skillets are made of iron; and though they are not so shiny and beautiful as copper or chromium-plated skillets, they are perhaps the best type of utensil for frying. 3. The advantages of iron skillets are: / a) Iron is a slow conductor of heat, as com pared with aluminum and copper, and so re tains its heat longer, thus providing a more even cooking temperature. b) For frying and broiling, the heavy, thick iron skillet is preferred for the same reason as above. c) Iron utensils are usually cheap and are very useful in the kitchen. d) The thick iron kettles with heavy lids are known as MDutch ovens.” They seem to cook more savory and palatable food because of the even temperatures maintained and because of tbe retention of juices, owing to the con densing of the steam generated and held with in the vessels* The disadvantages of iron skillets are: a) They are more difficult to keep clean* b) Iron skillets are quite heavy* G-alvanIzed-iron utensils are also used. a) Many garbage palls, washtubs, and water buckets are made of sheet iron covered with a protective coating of zinc* b) Iron treated in the above manner is known as galvanized iron. c) Iron rusts rapidly if exposed to moisture* For this reason, it cannot be made into con tainers for garbage or water unless covered by a protective coating. d) Zinc is relatively high in the activity series and consequently corrodes rapidly. However, the zinc oxide which is produced on the surface soon forms a thin, white, insol uble coating which protects the zinc from further corrosion. 60! I i e) Since zinc compounds are slightly poisonous, utensils made of this material cannot be used for cooking purposes. D. Enamel-ware. 1. Enamelware is made by coating an iron or steel utensil with a glassy, or vitreous, material. This material, enamel, is usually baked, or fired on the metal and is composed of sand, borax, and ; bone ash (calcium phosphate) or white clay. 2 . There should be no lead in it because of the poisonous nature of this metal. However, since the inclusion of lead oxide produces a heavier and harder enamel, it is often present in the enamelware on the market. 3. Enamelware is considered an excellent material for cooking utensils. a) The hard, glassy, surface is easily cleansed and is not reacted upon chemically by weak acids or alkalies; and consequently foods containing acids, such as tomatoes and fruits, should be cooked in enamelware pans or kettles. b) Unless subjected to sudden shock, which would cause the cracking or breaking of the enamel, utensils made of this material are very serviceable as well as economical. I f . . Enamelware which has become cheeked with small cracks should be discarded. 5. Every kitchen should include some enamelware. Copper. 1. Erom ancient times copper has been used for all types of household utensils and equipment. 2. It was the first metal that man learned to use. 3. The advantages of copper are as follows: a) Copper is frequently found in the free state and, being soft, is easily shaped. b) It is low in the displacement, or activity, series, therefore, it is easily reduced from its ores. c) Copper is soft, may be polished to a rich, red luster, and is an excellent conductor of heat. I f . . The disadvantages of copper are as follows: a) Copper compounds are poisonous. There is little danger if the utensils are kept bright and untarnished, but the housewife of today does not have the necessary time or energy to keep them spotless and bright. 62 b) Although copper is below hydrogen in the activity series and does not react with dilute acids, it does react with organic acids in the presence of air* c) Copper utensils are relatively high priced* 5>. Care should be used in cleaning such utensils not! to scratch through the plate* 6 . Food should not be allowed to stand in copper containers. F. Glass. 1* One of the marvels of modern chemistry is the production of a kind of glass which can be put directly over a flame. a) Common glass is made by fusing the oxides of silicon, calcium, and sodium. The fusion takes place at a temperature of about 2500° F. Under this intense heat the oxides combine to form what are known as silicates* Glass, therefore, is a mixture of various silicates. (1 ) tJhen the mixture cools, after proper heat treatment, called annealing, the silicates form a solid solution without crystallization. Crystallization may &3~! I occur after a long time, causing cloudi-: ness and brittleness. (2) The disadvantage of this common glass is that of its high coefficient of expan sion (that is, it expands greatly when heated), so that it breaks easily when it is subjected to changes in tempera ture . b) Hard glass may be made by using potassium oxide instead of sodium oxide. The real improvement from the standpoint of cooking came when boron oxide was substituted for t some of the silicon dioxide. This produced i a glass which is a mixture of silicates and borates. c) lfPyrexH glass is a trade name for a similar heat-resisting glass which contains a mixture of sodium and aluminum borates and silicates and free silica. (1 ) The presence of borates makes this glass' very resistant to heat changes because of its low coefficient of expansion. (2) This type of glass is very valuable be cause of its low degree of solubility and great resistance to temperature changes. It is now used for all kinds of cooking utensils, even for frying pans. 2. The advantages of glassware utensils are:. a) Glass utensils do not affect any kind of cooked food. b) Glassware is easily cleaned; therefore, there is little chance for the contamination of food with decomposed material. c) Poods may be served In the same utensil in which they are cooked. d) If not broken, heat-resisting glassware is the most durable of al3. kitchen-utensil material. 3. The disadvantages of glassware utensils are: a) It has poor conductivity of heat; the effect being the sticking of the food to the utensil. b) Since glassware is breakable, it may prove to be expensive if care is not used in han dling It. G. Pottery. 1. Perhaps the oldest form of cooking utensil and food receptacle is that made from clay and hard ened by fire* The first process in the making of pottery con sists of grinding dry clay into a powder and then adding water to make a paste* After a pasty mass has ; ,been formed, it is shaped by molds or on the potter f s wheel. This 1 1 green” pottery is then placed in a kiln, where it is thoroughly baked. In order to have a nonporous vessel, salt is thrown into the fuel bed at the bottom of the kiln. The salt vapor reacts with the clay on the surface to form a hard, impervious layer of sodium aluminum silicate. When properly made, pottery will stand a great deal of heat and may be used where a gradual, even heat is supplied. The earthenware or heavy glass casserole with a closely fitting cover and no steam outlet may be successfully used in the so-called waterless method of cooking vegetables* The cover should fit tightly and should not be removed during the cooking. A moderate temperature should be used to prevent burning; steam is generated slcmly from the water in the food itself. 7. When this glass casserole or one made of earthen ware is brought to the table in a metal casserole holder, it makes an attractive table piece. Exercises: 1. What changes have occurred in the use of kitchen equipment in the last fifty years? 2. Why should you know the applications of chemistry in the making and using of cooking equipment? 3. Classify and describe the important facts that you should know about cooking utensils. L j _ . What is the effect of aluminum on foods? 5# How should aluminum be cared for? 6. How is iron plated with tin? 7. Compare the various kinds of materials used for the making of cooking utensils as to utility, effect on foods, and attractiveness. 8. What is enamelware? 9. How does heat-resisting glass differ from ordinary glass in composition and utility? Extra problems: 1. Make a detailed cost study of the cooking utensils needed to equip an ideal kitchen completely. Write to various companies that make cooking utensils and assemble information regarding the methods by which the utensils are manufactured. Make a study of the historical development of cooking utensils and report your findings to the class. Make a collection of the advertisements of cook ing utensils and compare the claims which are made with the actual facts that you have learned or can experimentally verify. TOIT IV THE CHEMISTRY OP TABLEWARE Early man made use of crude vessels for the storage and preparation of food. As metalworking was perfected, knives, spoons, and later, forks came into use. Only the wealthy could afford them at first, and each individxial carried his own about with him. As metalworking became more productive, the ordinary man had his individual knife of inexpensive metal, while the nobility had spoons of silver and gold and knives with ornamental handles. Today the housewife is thrilled as she goes through the chinaware and tableware department of a large store. Beautiful silver service and exquisitely decorated chinaware greet her eyes. To the modern homemaker utility seems to 'have become of secondary importance; instead she is more interested in the beauty of design and the coloring of her tableware. Purposes; The purposes to be achieved in this unit are the following: 1. To learn how tableware is made. 2. To determine the factors which should be consid ered in the selection of tableware. 3* To learn how to care for and to clean tableware properly, l±. To learn how to purchase tableware economically. Problems: The problems to be solved in this unit are: 1. How is silverware made? 2 . How may you buy plated silverware intelligently? 3. How should silverware be polished and cared for? i j . . How is dinner ware made? Word list: j Electrode: a conductor through which a current enters or leaves. Porcelain: a vitreous, more or less translucent, ceramic body or ware; china. Problem I: How is silverware made? A. Hinds of silverware. 1, Silverware and other metal tableware may be classed as flatware and hollowware. a) Flatware consists of knives, forks, and spoons. b) Hollowware consists of bowls and other vessels. 2. Silver is a fairly soft, white metal which is capable of a high polish. It is often found in . the. free . stateJLt is also f ound mixed with the_ ores of copper, gold, and lead. 3. Since silver occurs in the free state and is easily extracted from its ores, it is one of the oldest metals known and used by man. Ip. The purest form of silver used in tableware is called sterling silver. Its standard composition that is fixed by law, is 92.5 p©** cent silver and 7*5 P©r cent copper. 5. Silverware is made by molding the object from molten metal or, more often, by rolling and stamping the object from sheet silver. 6. The design is usually lfstuck1 1 upon the metal by a dye, though it may be etched or hammered. 7. Sheffield plate, a kind of silverware, may be made by rolling, into a thin sheet, silver and copper which have been soldered together in the form of a bar. It is more common today to make it by electroplating the silver on the copper after the object has been shaped. 8 . Most tableware sold today is silver-plated. a) Plated silverware is made by first stamping the knife, fork, or spoon from a metal which is cheaper than silver. b) This metal may be German silver, which 71 contains no silver at all but is 52 to 60 per! cent copper, 1 to 22 per cent nickel, and 25 per cent zinc, or, more generally, sheet iron or steel* c) The article is then plated with silver by an electroplating process. B. Silver-plated tableware. 1. After the object, such as a knife, fork, or bowl, has been shaped from the inexpensive metal, it is given a coat of silver by a process called electroplating. The object must be perfectly clean otherwise the silver will not stick to the j metal. 2. The amount of plating that an object will receive depends on the strength of the electric current and the length of time that the object is left in the solution. Thus tableware that is to be heavily plated has a stronger current applied to the solution and remains in the solution longer than ware that is to be lightly plated. 3. Gold-plating, nickel-plating, and chromium- plating are carried out in a similar manner. Plating with gold, nickel, and chromium is not as simple as it may seem, as many factors enter into the process. Other chemicals are added to the electrolyte to aid in the electrolysis during the' plating process. 1^. After the object has received a sufficient coat ing of silver, it is thoroughly washed and polished to a bright finish. 5. Some hollowware, particularly objects which will not need to be washed in the home, are covered with a thin coating of lacquer to preserve the bright finish and prevent tarnishing. Exercises: ! 1. Why do archaeologists frequently find decorated pots and bowls in prehistoric ruins? 2. What purposes do chinaware and silverware serve? 3. Why should you study tableware in a chemistry- centered subject? I f . * What is the difference between flatware and hollowware, and what is sterling silver? 5. How is sterling silver made? Problem II: How may you buy plated silverware intelli gently? A. Silver-plated flatware is made in many grades accord ing to the thickness of the plate. The government 73! I has set up certain standards for plated flatware. B. In general, one may regard as true that the thicker the plate is, the longer the life which may be expected of the silverware. But no matter how super ior the grade of silverware, it is bound to wear, more or less according to how often it is used and how much care one bestows upon it. C. The better grades of flatware contain reinforcements at the points of greatest wear. The reinforcements are made either by inlaying blocks of silver or by overplating at these points of wear. D. Silverware purchased in sets is more economical than that purchased by the piece. If the set has more pieces than are in constant use, they should be used in rotation so that they may wear evenly. E. Knife blades should be ma.de of stainless steel. This steel contains the metal chromium. It resists the corrosive action of fruit juice and other foods. Exercises; 1. What is triple-plated silverware? 2 . Hoi'i can you buy silverware intelligently? Problem III: How should silverware be polished and cared for? 7k I A. General care* 1 * Silverx^rare should be stored where it is protected from continued exposure to moisture and impuri ties in the air* 2. Flatware are better protected if wrapped separately in a soft cloth* 3# Silverware should never be allowed to stand over night before washing, since this practice invites tarnishing* Moreover, since food soon dries on silverware, it is harder to clean after it has stood awhile, and there is more danger of scratching the finish when it is washed* k. Silverware should be washed in hot, soft water with a neutral soap, rinsed with hot water, and dried with a soft cotton cloth, 5k Hollowware should never be piled in the dishpan, but each piece should be washed separately* 6, Lacquered pieces should not be washed, as water causes them to peel. If they do peel, alcohol will remove the rest of the lacquer, and the pieces may be refinished with a new coat of clear lacquer* B, The causes of tarnish and its removal, 1* Silver is relatively low in the displacement series and is not easily corroded. It does not oxidize in the air to form an oxide. The brownish or black tarnish which often occurs on silver articles is its sulfide which forms when the metal comes in contact with foods con taining compounds of sulfur or is acted upon by air containing hydrogen sulfide. Eggs or foods prepared with eggs contain sulfur compounds which easily tarnish silver. In regions where a great deal of coal is burned, silver tarnishes rapidly because of the sulfides present in the smoke of the atmosphere. When silverware is wrapped for storage, a rubber band should not be used to secure the wrapping. Rubber contains sulfur, which will cause the silverware to tarnish. There are many commercial devices on the market for the removal of tarnish from silver, some of which are often called electrolytic silver- cleaner s . a) One such type consists of a special pan containing an aluminum sheet or tray. Some times only a sheet of aluminum is sold, with directions for its use. The silver articles ape placed In the pan in contact with the aluminum sheet, and the pan Is filled with a warm solution of baking soda and salt. The solution Is then allowed to boil. The articles are left In the solution until the tarnish disappears, then removed, rinsed, dried, and polished. It is unnecessary to buy the electrolytic metal sheets, as the same results can be obtained if the silver is placed In any aluminum pan and the solution added as described above. This process of i cleaning silverware does not remove or in- 1 jure the silver in any way. b) There are a number of silver polishes on the market, and the housewife Is often puzzled about which to select. (1) Silver polishes should contain no grit. (2) The removal of the tarnish is due to the abrasive action of some material such as powdered or rotten stone, or whiting. (3) Some commercial cleaners contain sodium bicarbonate, wax, or glycerin. The function of the soap and soda is chiefly to act as a cleaner by removing the 77 i grease and dirt from the surface of the : silver. They do not have much effect on the tarnish. This is removed through the scouring action of the abrasive. (4) The coarser the abrasive, the more rapid its action. However, a coarse abrasive will remove a considerable amount of silver. It follows, then, that a rapid-’ acting polish is not the best. (5) The housewife should test commercial polishes by rubbing a little of each type over the fingers or fingernails \ and should select the one containing the. least amount of grit. c) Silver polishes containing cyanide compounds are poisonous and should not be used. d) Tarnish preventives are chemicals used in silver chests to remove the sulfur compounds from the enclosed air. They are effective only when a chest is kept tightly closed. 6 . The housewife may find it more desirable and safer to make her own silver polish. This may be done by purchasing a small amount of an extra- fine grade of whiting from a paint store. A I paste can be made by mixing the whiting with a little household ammonia, pox-jdered neutral soap, ■ and water. This polish may not be so rapid in action as commercial polishes, but there will be . less danger of scratching the silver. This polish becomes hard rather rapidly so one should make only the amount needed. A polish which keeps longer may be made by this formula (or recipe): 3 level tablespoonfuls of powdered neutral soap J ounce of glycerin lj ounces of hot water 1 teaspoonful of household ammonia The mixture should be stirred well, and a. suffi- ; cient amount of an extra-fine grade of whiting should be added to make a firm paste. The polish should be kept in a , tightly closed container. 7. A soft flannel cloth should be used to apply the polish. The silver should be rubbed until clean, then wiped free of polish with another soft cloth followed by washing in and with warm water, rinsed, and dried. Exercises: 1. How should silverware be stored? 2«_ How should silverware be washed? 3* How should lacquered hollowware be cared for? I 4. . Hhat substances cause the tarnishing of silver ware ? 5 . Mhat foods are most likely to cause the tarnish ing of silverware? 6. How may you polish silver by the electrolytic method? 7. What do silver polishes contain? How do they work? 8 * How can you make your own silver polish? Problem IV: How is dinner ware made? A. Chinaware, or porcelain ware, was first made by the early Chinese. B. All early peoples were masters of the art of making pottery. However, the Chinese were the first to bake a dish with a hard body and a beautiful glaze. Many times a beautiful color design was embodied in the glaze. In modern times porcelain is produced in many of the European countries notably England, Germany, Prance, and Italy, and in the United States. C. A common question that arises pertains to how dishes are made. 1 . The best material of porcelain dishes is clay. . 2. ..Feldspar, sand, .ground .flint, or bone ash is also, added to produce a particular texture. 3. There are many types of clays which may be used. Clay is a mixture of silicates, such as kaolin and feldspar. a) Clay composed of pure hydrogen aluminum silicate is called kaolin and is white. Fi»om it is made the finest white chinaware. b) The process in making chinaware is rather complicated. (1 ) The pulverized clay is first mixed with water, after which pebbles and other hard objects are removed by running the mixture through screens. Then the water' is removed from the clay, and it is ready to be mixed with the other ingre dients which are necessary in the manu facturing of chinaware. (2) The kinds of materials added.depend on the quality of the chinaware to be made. One common quality is made by mixing the clay with powdered feldspar and flint. Water is added to the mixture, and it is thoroughly stirred by machinery until it has the consistency of bread dough. The 811 i plastic mass is then ready to be shaped , into the desired object by means or a potterrs wheel or by pressing it into molds * (3 ) The dinnerware is dried and then placed in cylindrical cases made of fire clay, called saggers; then these are put in the kiln, and. the ware is fired. The saggers protect the dinnerware from the soot and ash of the fire and ensure even heating. The firing lasts from thirty- ' six to forty-eight hours. When removed . from the kiln after this first firing, ; at about 22f?0° F, the ware is hard and porous and must be glazed before it can be used. The style of kiln, time of firing, and heat vary with the different grades of ware. ( I } . ) The process by which a glaze is put on the articles consists of dipping, spray-, ing, or brushing the articles with a mixture called !,slip.t ! This mixture is made by grinding such substances as feldspar, flint, and litharge (lead oxide) to a fine poitfder and mixing with I water to the consistency of cream* After being dipped, brushed, or sprayed with this mixture, the article is left to dry. It is then placed in the kiln and fired a second time to a white heat, which produced a glaze. i (5) Glazes vary in chemical composition with, the materials used in the tfslip.f f After firing, the ware is hard, smooth, and glassy. The degree of translucency varies greatly, (6 ) The body of the ware and that of the glaze are made of t wo different materi als, They have different rates of ex pansion and contraction when heated and cooled. For this reason, the firing and cooling must be done gradually; other- x*rise the glaze will check, or show minute cracks. Fine china is fired at higher temperatures than ordinary china, and usually the glazed surface does not check. c) Decorations may be applied either before or after the glaze and are fired in decorating kilns. (1) If the designs and colors are put on be fore the second firing, the decoration is called underglaze decoration. (2 ) When the decoration is applied to the ware after it has been glazed, it is called overglaze decoration. i) Underglaze decoration is more perma nent but is limited in range of color to those colors which can stand the high temperatures to which they are subjected, ii) Certain colors cannot be applied as underglaze decoration since they change in firing. Applied designs are also used. One method of applying .designs is to use a lithographed transfer paper called decalcomania. The designs are then transferred to a special paper. This paper is applied to the ware face down and soaked off with xmter, which leaves the designs on the surface of the dish. The colors are then mixed x^Ith a flux to help them to fuse with the ware when fired and cooled. e) Designs on china may be painted by hand* Since hand-painted colors tend to run togeth er, several firings may be necessary if more than one color is used. D. Types of dinnerware are known as chinaware, porce lain ware, and earthenware. 1. Chinaware and porcelain ware are generally used interchangeably in naming the better qualities of dinnerware, although dinnerware sold under either name may vary greatly in quality. Some retailers call the poorer qualities of dinner- ware earthenware, and others use the term semi- porcelain ware. 2. Earthenware, other than described above, is also used in referring to flowerpots and other un glazed articles. E. The best quality of chinaware is made from the finest of materials; the workmanship is of the highest quality, and the manufacturing process is very care fully controlled. Because of the great variations in the quality of dinnerware, it is important that housewives know some of the factors which should be 85 considered in the selection of dinnerware. i P. Dinnerware should be selected on the basis of beauty, durability, and usefulness. 1. Quality of material: The best quality of china- ware is translucent, and when struck with a wood en mallet, it rings clearly. Dinnerware of poor quality is opaque, and when struck, it gives a dull sotind. It is always a good policy to exam ine dinnerx*jare closely for cracked and chipped places. These imperfections may be detected by dropping red ink on the surface. If the glaze is| cracked or chipped, the ink will be absorbed and 1 will be hard to remove. 2. Color or design: The pieces of the dinnerware should be examined for color and design blemishes and the way the design has been put on. 3. Practicality: Though thin china is very desir able, one should take thought before selecting it for everyday use, for it may be too fragile for such use. I f . . Grades: There are usually five grades of wares put on the market by manufacturers. a) Selects: These contain no blemishes. b) First grade: Slight blemishes which are not 8 6 j easily observed. I c) Second grade: A few more slight blemishes which are not easily observed. d) Third grade: A cheaper grade, more blemish es . e) Culls or lumps: Worst grade. G. The constimer can place little faith in the statement that a certain pattern is in open stock. It seems that all patterns are open stock during the time of purchasing but when one wants and needs extra pieces to substitute, the stock is always nclosed.T I All imported ware must bear the name of the country in which it is made. Unmarked ware is made in the United States. II, Glass dinnerware is also popular. There is a need in every home for some type of glass ware. 1. Glass is used for dinnerware, electric-light bulbs, bottles, glasses, jars, mirrors, and windows. 2. Ordinary glass, as it was discussed in Unit III, is made from sand, sodium sulfate, sodium carbon ate, and calcium carbonate of limestone. Many different types of glass, with varying proper ties, may be made by adding or substituting other metallic compounds. a) Ordinary glass is the softest, most easily worked, and cheapest glass. Prom it are made bottles, cheap dinnerware, and ordinary win- down glass. b) The substitution of potassium for sodium and of lead for calcium gives a much harder and more brilliant glass. This type of glass is , used for the manufacture of fine tableware, such as cut glass. It is also used in making optical and camera lenses. c) Iron compounds usually occur in sand and givei glass a green tint. This can be seen by looking at the edge of a piece of window glass. This green color may be lessened by adding manganese dioxide to oxidize the ferrous iron to ferric iron, which imparts only a slight yellowish tint to the glass. d) Colors in glass are obtained by adding color ed mineral salts or oxides to the molten glass. Designs on glass dinnerware are obtained by molding, cutting, sanding, or etching. (1) The molds, Into which the molten glass 8 8 l I Is poured and blown, may have designs Imprinted or overlaid. Thus, the ware had a design on it when cooled. (2) Glass may he cut with emery wheels or other abrasives. (3) A fine stream of sand blown against a glass vessel may be lised by a skilled workman in cutting designs. ( I j . ) Etched glass is made by first covering the article with wax, followed by cut ting the design into the wax so that the glass surface is exposed. Hydrofluoric ; acid or the fumes of this acid are 1 allowed to come in contact with the ex posed glass. This acid reacts with the glass, cutting the design which had been previously made in the wax. The wax is then removed, and the glass is left with the etched design. (Light bulbs are frosted on the inside by injecting a stream of hydrofluoric acid into the bulb and then washing thoroughly with water.) Exercises: 89| 1* What substances go into the making of dishes? 2* How does fine chinaware differ from cheap pottery? 3# Describe the process of making dinnerware* I j . * Describe the kilns in which dinnerware is fired* 5. What is nslip!f? 6* How are colored decorations put on dinnerware? 7* What grades of dinnerware are manufactured? 8. How is glassware for table use manufactured? 9* How is colored glassware produced? 10* What causes common glass to have a greenish tint?1 11. What substances are used in the etching of glass? 1 2. Hoi* is etching accomplished? Extra problems: 1. Hake a study of the early history of glass* 2* Make a list of the uses of glass. 3. How is stained glass made? ] - ] . . What is spun glass, and how is it used? 5* What is glass wool, and how is it used? 6. Make a list of the mineral salts used to produce the ' various colors in glass. 7. Make a list of the various glass dishes used in the home. 8* What kinds of glass vessels may be used in the 9. 10. 11. 12. 13. 14. 90| i kitchen? What is meant by tempering glass in the manu facturing process? Explain why lead glass is more dense than ordin ary glass. Why does good cut glass give a metallic ring when struck suddenly? Why should glass dishes be tempered by being warmed before hot liquids are poured in them? Why is a metal fork or spoon placed in a fruit jar before something hot is poured into it? Why will glasses sometimes break if hot water is ; i poured into them? x mit v THE CHEMISTRY OP FABRICS The making of clothing or textile fabrics is one of the oldest of the industrial arts. The skins of animals were man’s first clothing materials. Later he discovered that nature produced other materials which he could make •Into better clothing fabrics. Since those early days, man has continually found additional raw materials of nature from which he can make clothing. Today, the textile in dustry is one of the largest businesses. The purposes to be achieved in this -unit are as To broaden one’s understanding of the reasons for wearing clothing. To learn the chemical properties and character istics of the different kinds of materials used in making clothing. To help one to recognize the different fabrics. To assist one in buying clothing wisely and economic ally The problems to be solved in this unit are: What is the function of clothing? What..are, the properties .and.characteristics of. Purposes: follows: 1 . 2. 3. k. Problems: 1 . 2. clothing materials? 3* How are fabrics dyed? ! { . * What simple chemical and physical tests may be used in identifying fabrics? Word list: Synthetic: pertaining to compounds formed by chemi cal reaction in a laboratory, as opposed to those of natural origin. Textiles: any material that is woven. Problem I: What is the function, of clothing? A. Clothing is necessary for modern life. Modern life demands an extensive use of clothing for many rea sons. Decency and good moral standards demand that clothing be worn. Though it may be true that one wears too much clothing, people recognize the moral need for clothes to cover the naked body. B. Health demands that the body be clothed. The body is equipped by nature to adjust itself partially to changes in the temperature of its environment. During cold x^eather nature functions best with the help of clothing because clothing retards the evapor ation of perspiration, and thus the heat of the body is retained. Our primitive ancestors xdio wore no 93j clothing must have had a difficult and painful time j recovering from scratches and other injuries to their naked bodies* The span of life was extremely short, and there is no doubt that the lack of clothing, with the attendant exposure of the person to infections of all kinds, was a principal cause of this shortness of1 life. 0. Clothes have an influence on mental health. Both mental health and physical health will be better if a person is able to feel that he is attractive. The uses of the many beautiful multicolored fabrics, products of the chemistTs test tube, will help to ; develop that self-confidence which is an important part of mental health. Exercises; 1. Why does modern living demand more clothing than was formerly necessary? 2. List the ways in which clothing protects the health of the body. 3. What part does chemistry play in the clothing industry? Ip. How have new kinds of clothing increased the joy of living? P° clothes have an influence on mental health? Problem II: What are the properties and characteristics of clothing materials? A. Fabrics made from animal fibers. Animals furnish many fine fibers out of which one can weave clothing materials. The most important of these are the hair fibers, such as wool from sheep, and silk fibers from the cocoon of the silk worm. All animal fibers are proteins. 1. Wool is the warm fiber. a) The chemical elements in wool are oxygen, nitrogen, hydrogen, sulfur, and carbon. The molecules of wool fibers are big, containing dozens of atoms of each of the foregoing elements. The presence of protein in all wool is proved by the fact that any wool fiber will respond to the tests for proteins. b) A single wool fiber may be from one to ten inches in length and may vary in thickness from one three-thousandths to one five- hundredths of an inch. Those fibers which are from eight to ten inches long and from one three-thousandths to one two-thousandths inch thick are the most desirable ones from which to weave cloth. 95 c) The Associated Wool Industries list the following general characteristics of wool as the reasons for its being prized as clothing material: (1) It is a natural body covering, (2) It is thermostatic; that is, it protects from both heat and cold, (3 ) It is porous and absorbent, allowing the1 skin to breathe and absorbing perspira tion, ( I | . ) It is fire-resistant in that it does not flare up easily. (5) It is elastic, and therefore clothing made from it holds its shape. (6) It is strong, durable, light, and soft. 2. Silk is known as the fiber of kings. Most silk is obtained from the cocoons of a particular type of silkworm known as the mulberry silkworm. There are many other silkworms which produce cocoons of silk, but they are not cultivated as the mulberry silkworms are. a) The silk fiber is formed by the silkworm to cover Itself so that It can go through the pupa stage. The fiber is really made up of 96 two different substances, known as fibroin and sericin. The fibroin is secreted by two glands in the upper part of the body and comes out through a tiny opening in the head. But just before it emerges, the sericin is secreted into the same exit tube and cements the two fibroin filaments together into a single thread. The fibroin coagulates, or hardens, just as it comes in contact with the. air, and, when one finds, it is covered with the coating of sericin. (1) Both fibroin and sericin are proteins ! and contain the elements oxygen, hydro gen, carbon, and nitrogen. (2 ) They have been analyzed and found to contain nine different amino acids. b) The silk fiber is one of the finest fibers obtainable and the longest natural one. The diameter of a single fiber may be from five ten-thousandths to seven ten-thousandths inch, and its length may be from 1000 to lIpOO yards. c) The good properties of silk are the follow ing: (1) Silk is extremely lustrous* _ . . (2) It is -unusually strong. (3) It is very elastic. (If.) It is hygroscopic and, under certain conditions, will absorb as much as 30 per cent of its own weight without feel ing wet. (5) Silk fibers will take most dyes readily. Purs and leather. These materials were easiest for early man to sew into large pieces, and most of his clothing needs were satisfactorily met by the use of furs and skins. a) Purs, as one uses them for clothing, are the hair-covered skins of animals. Purs are warm because a large amount of air is trapped between the tufts of hair and under the scales of each hair. The length of fur hairs and the general condition of fur depend upon the following: (1) Diet and food supply of the animal; (2) Temperature of the climate in which the animal grew; (3) Whether the animal was trapped before or after hibernation; and (if) Amount and temperature of the x^ater if the animal lives in water, b) Leather is the processed, or tanned, skin of an animal from which the hair has been re moved* Leather is a useful kind of clothing material because it serves a variety of purposes. (1) It is ideal to protect our feet from wetness, injury, and cold. (2) Leather is the best material yet dis covered for covering the hands. (3 ) It is valuable for jackets, vests, and ! coats because it wears well and is warm. (Ip) Many miscellaneous articles are made . from leather. (5) Leather clothing is warm, largely be cause it prevents the entrance of air and hence retains body heat. B. Fabrics made from vegetable fibers. Cotton and linen are the two more popular vegetable fibers used in the making of textiles. However, one must remember the jute, ramie, and hemp that are also vegetable fibers from which various articles are made. Each of these are discussed x^ith as few details as possible* Cotton. Cotton is the most widely used plant fiber in the making of clothing. Cotton fibers are the hairs which grox^ about the seeds of the cotton plant. Chemists know the substance as cellulose. It is a carbohydrate and belongs to the same family as the sugars and starches. a) The cotton fibers vary in length, or staple, as it is known in the textile trade, from i three fourths inch to one and one half inches for American cotton and from two to three inches for that grown in Egypt. Each cotton , fiber is a single cell. b) The reason cotton is popular is due to these factors: (T) Cotton fibers are easy to spin because of their natural twist. (2) Cotton is very durable. (3 ) It absorbs water well but not as well as wool or silk. ( i j . ) The fibers are not damaged by hot water, and therefore cotton fabrics may be washed and sterilized repeatedly. Linen. Linen fiber comes from the inner bark of the stalks of the flax plant and, like cotten, is 100| ! practically pure cellulose. a) The fiber is long, lustrous, absorbent, and smooth. The length., averages eighteen inches. It is very inelastic and difficult to dye. These qualities limit its use, but, for some purposes, it is unsurpassed as a fabric. Linen fibers are stronger and harder than those of cotton but less elastic. It Is a better conductor of heat and therefore feels cooler to the touch than cotton. b) Under the microscope the fibers have the i appearance of bamboo canes with jointed cells and split tapered ends. Linen fibers appear . translucent; cotton fibers appear opaque. 3. Jute and hemp. %Jute and hemp are plant fibers which come from plants related to the flax family. Jute and hemp are composed of a sub stance known as lignocellulose (a woody, simple cellulose). Chemically, they differ from linen and cotton, and the fibers are not fine enough for most clothing purposes. However, these fibers are used extensively for the making of carpets, twine, and sacks, ip. Ramie. Ramie, or China grass, is the fiber of a 101 plant belonging to the nettles. It makes a very good fiber for clothing because it is strong, durable, lustrouts, and less harsh than linen. It is not used as widely as cotton or linen because, in separating the fiber from the cementing plant tissue, much hand labor is necessary. This makes the fiber costly. . Fabrics made from artificial fibers. It was not un til about 1911 that there was put on the market a new fabric material made from regenerated cellulose which could compete with nature^ materials. Today one t finds a multitude of synthetic fabric materials. j These new fibers should be thought of, not as imita tions- of, or substitutes for the natural fibers, but as new products each with its own virtues and its own uses. 1. Rayon. Rayon is made from cellulose taken from the wood of trees or from cotton and, by various chemical processes, converts it into a viscous stibstance which can be forced through tiny holes, thus producing rayon, a) RayonTs disadvantages are: (1) It is very inelastic. (2) It loses its strength when wet. University of Southern f^Hfornia Library 102| i i b) Rayon’s advantages are: (1) The fiber can be made any thickness one desires. (2) The material is very smooth and thus is resistant to soiling, moreso than the natural fibers. (3) Rayon fabrics do not mildew easily, and the white rayons remain perfectly white even after repeated washing. 2. Nylon. Nylon is made from substances known as diamines and dibasic acids, which can be synthet-j ically produced from the common rax^ materials coal, water, and air. It is all based on how the small molecules unite to form, large molecules, also known as polymerization. The large mole cules so formed are called “polymers” and can be likened to growing plant tissue. The advantages ' of Nylon are so great that the market is very popular. The two greatest advantages of Nylon are: Its high elastic value and its high tensile strength. 3. Vinyon. This fiber should not be confused with Nylon, although both fibers have been an out growth of years of experimentation. Vinyon Is made from a vinyl resin derived from coke, lime, 1 ■water, salt, and other substances. Like Nylon, it is a true synthetic fiber with a chemical base. 1 1 Vinyon1 1 is a product of the American Viscose Corporation and is really the trade-mark name of resins. Vinyon resists fire, water, bacteria, and mineral acids, also serves as a binder so the garments will not shrink. It is a < silk-like fiber. I } - . Velon. This is very similar to Vinyon. 5. Saran. Like Vinyon, Saran is a thermoplastic. Its basic raw materials are petroleum and salt. This fabric resists chemicals, fire, water, grease, stains, and mildew and is not attacked by moths or insects. 6. Orion. This is a synthetic fiber known as a polyacrylonitrile fiber. It is made in continu ous filament form. It has many Industrial uses as well as for rainwear, underwear, bathing suits, men's shirts, linings, and tricot fabrics. Also, it Is used for curtains, awnings, and win dow shades. 7. Lanital. Lanital fibers are made largely from the casein, of milk. Lanital has much the same l o l l . chemical composition as natural wool, but the fibers lack the scales of natural wool, and con sequently it cannot be woven into a warm fabric. 8. Other fabrics. There are new synthetic fibers being experimented and developing but no inform ation has been available to a great extent. Exercises: 1. 'What clothing fabrics are obtained from animals? 2. Why is wool warm? 3. What chemical elements are found in animal i . r fibers? i|. How does wool differ from silk in chemical compositi on? 5. What mineral substances are used in the manu facture of clothing? 6. Sow does wool vary in quality? ?• Show by drawings the relative lengths and diam eters of wool, cotton, and silk fibers. 8* What are the two protein materials found in silk? 9. How does rayon differ from silk? 10. What are the essential differences in composition of rayon, Nylon, and silk? 11. What is the approximate composition of furs and__ ! io 5 | skin? 12. What is the chemical composition of cotton? of linen? 13. What is the chemical composition of rayon? lip. What are the good qualities of rayon? l5* What are the poor qualities of rayon? 16. Do you think that the synthetic fibers will re place natural fibers for clothing materials totally? Problem III: How are fabrics dyed? A. Man seeks to capture the beauties of nature. He probably wanted to transfer the juice of berries^to his clothing in an effort to produce a decorative effect. Thus, dying began. B. There are two types of dyes. 1, Natural dyes. These are obtained from nature, though they may be purified by man. Some of the 1 common natural dyes are indigo blue obtained from the indigo plant, grown principally in India; Turkey red, obtained from madder root; a.black dye obtained from logwood; a brown dye from butternut hulls; and a scarlet dye obtained by grinding an insect called cohineal. Natural dyes' are often dull in color and soon fade. The number of different tints which can be obtained is small. Synthetic or artificial dyes. When coal is sub jected to destructive distillation in the pro duction of coal gas and coke, one of the by products is coal tar. Destructive distillation is the process of heating some combustible sub stance to a high temperature in the absence of air. VJhen materials such as coal or wood are thus heated, some of the complex organic com pounds are broken down into simpler substances, and these, with the other volatile substances in the coal or wood, are driven off in the gaseous state, or the by-products. The principal products in the case of coal and wood are coke and charcoal. From coal tar are obtained such chemicals as naphthalene (moth balls), benzene, toluene, phenol, and anthracene. By a series1 of complicated chemical steps in which other atoms or radicals are added to the compounds named above, many beautifully colored dyes are pro duced. These man-made dyes have the following advantages: a) Synthetic dyes may be produced for about 20 107| per cent of.the cost of natural dyes. b) Synthetic dyes are more brilliant. c) The colors of synthetic dyes are more ”fast.rr 1 d) Many thousands of shades and even many new colors are now available from synthetic dyes. e) Synthetic dyes are made under controlled conditions, are purer, and are uniform in quality. G. Garments may be dyed in the home. Many housewives find it economical to dye such articles as dresses, curtains, and bedcovers in the home. This process is not necessarily difficult if certain precautions are ■ followed. It is usually safe to use any of the nationally advertised dyes, provided the directions on the package are followed carefully. 1. It is important that the exact kind of material of which the goods is made be known. 2. It is essential that the correct temperature be maintained. 3. Dark-colored goods cannot be dyed with light colors unless the goods are first bleached. Ip. Directions for bleaching out the dyes already on the goods are given with the dye materials provided. 5. It is often wise to take a small piece of the material to dye as a test sample In order to ensure that the correct shade will be obtained. Exercises: 1. Why did early man attempt to color the materials he used? 2. Consult some old person and ask how cloth mater ials were dyed In his early youth. Write up your interview. 3. What advantages do synthetic dyes have over natural ones ? l | . . What precautions should be observed in dyeing fabrics in the home? Problem IV; What simple chemical and physical tests may be used In identifying fabrics? A. The old method of identifying fabrics was simply to feel and look. But this was before the many'new fibers of today were on the market and before manu facturers had developed the art of mixing many kinds of fibers in the making of a single fabric. It is not an easy matter to analyze completely or identify all fabrics. However, here are some tests which may be applied to most fabrics. The strength test. The quickest and most con venient method of testing the tensile strength of a fabric is to grasp it firmly between the thumb and forefinger of each hand. If the tensile strength Is low, the thumbs will go through the cloth easily. The breaking test. This test enables a person to determine the kinds of fibers that are used In the warp and filling of the fabric. To apply this test, draw a single thread from both the warp and the filling, untwist the yarn, hold the ends in either hand, and break the yarn with a ' quick pull. The ends of the broken fibers will ! appear as follows: a) Cotton. A fuzz tuft of fibers will show at both ends. b) Linen. The break will be Irregular, and the . fragments will be pointed. c) Wool. The ends will have a x^avy appearance. d) Silk. It will break straight, and the fibers will be long and lustrous, e) Bayon. It will look something like cotton but lustrous, The burning test. It is best to use individual threads pulled from the warp and rilling for this- test, although bigger samples may be used to con firm one1s conclusions. The equipment for the burning test is simple. Use a flat white plate or pan and a small flame such as a match flame or candle flame. One should practice on known fabrics until the senses of perception and dis cernment are developed. a) Cotton: Cotton fibers burn readily with com paratively little odor and leave very little ash. It smells like burning paper. b) Linen: This burns more slowly than cotton i and has an odor of burning rope. When the fire Is out, the ash is In the form of the cloth. In a short time*, the ash falls off. c) Wool: When a flame is applied to animal fibers, they give off the plainly disagree able odor of burning feathers or hair. A gummy bead of black residue will accumulate on the ends of the threads of animal fibers. d) Silkr The cloth burns rather slowly and gives off a decided animal odor. After the fire is out, the residue is in the form of gummy balls or beads along the burned edge. Ill e) Bayon; All rayons burn very quickly. The viscose and cuprammonium rayons leave practi cally no ash if the samples have little weighting. Burning acetate rayon gives off an odor of burning punk. Little sparks can often be seen. It leaves a shiny bead simi lar to that of silk, except that the bead is harder and does not crush easily between the finger and thumb, as the silk bead does, L j _ . The hydroxide test. This distinguishes wool and silk from others. By putting all types of fabrics in this solution, boiling for about ten minutes, any wool or silk will dissolve whereas the others remain. 5. Mitric acid test. If a few drops of nitric acid are put on various kinds of fibers and warmed, silk and wool turn yellow while cotton, linen, and rayon are not changed in color. 6 . Miscellaneous tests. There are numerous other tests for fabrics which are only worth mentioning here, such as the ink test, the oil test, the saliva test, the water test, and the tearing test. 112! Exercises: 1. Describe and illustrate the breaking test for identifying fabrics* 2. Describe and illustrate the strength test for i dent ifying fabr i c s * 3. How may the burning test be applied in identify ing fabrics? i|. List the methods that you would use to determine the presence of cotton and linen in a piece of goods * 5* How could one tell whether a piece of goods was made of cotton or wool or a mixture of the two? 6 . If you suspected that a nsilkf f dress contained rayon, how could you be sure, one way or the other? 7. What identifying tests could you make to show the presence of a cotton and acetate-rayon mixture in a piece of goods? of a cotton and rayon mixture?, 8 . How does concentrated hydrochloric acid affect the different fabrics? 9. What solution would you prepare to show whether a piece of goods was made of animal fibers or vegetable fibers? 10* What chemicals are used to determine the presence of acetate rayon? of silk? 11.3 Extra problems : 1. What are the latest developments in the making of synthetic fibers for clothing? Write to the Bureau of Home Economics, Department of Agricul ture, Washington, D. C. 2. What information about construction, fiber con tent, color, and durability is available on the labels of clothing sold in your locality? 3. What is being done by the government and textile manufacturers to promote better labeling of textiles? Ip. What is the price range of suits, dresses, and overcoats sold in your shopping center? 5* What are your state and local governments doing to promote honest advertising of textiles? 6 . Collect as many samples of different fabrics as you can obtain from local stores and test them to determine what fibers are present. 7. How are the strength and durability of fabrics determined by mechanical methods? Could you devise an apparatus to test the wearing quality of stockings? 8. How may one determine the difference in heat conduction of different kinds of fabrics? 9# How are dyes made from coal tar? 10# What methods of cleaning and mothproofing are used in your community? 11# How has the mass production of textiles lowered the cost of clothing to the average consumer? 12# How does the clothing of the people of different nationalities differ? 13# What specific knowledge must you have to buy clothing and textile fabrics intelligently? UNIT VI THE CHEMISTRY OP STAIN REMOVING Valuable linens and clothes may be permanently spot ted if stains are not removed before laundering* Hot water may set protein stains, such as egg, blood, or meat juice and soap suds may set others, such as coffee, tea, or fruit 'stains* So to be safe, remove all stains before laundering, Purposes: The purposes to be achieved In this unit are the following: 1 . To learn what materials should be used in spot removing. 2. To learn the general rules of removing stains. 3. To become acquainted with how to remove various types of stains on different materials. Problems: The problems to be solved in this unit are: 1. What are the different types of stain removers? 2. How does one remove specific stains? Word list: Solvent: having the power of dissolving. Stain: a discoloration produced by foreign matter; a spot. Problem I: What are the different types of stain removers? 116 A# There are three general classes of stain removers. Keep one or two of each on hand and one will be supplied with the basic elements. 1* Solvents. Benzene or carbon tetrachloride (dry cleaning fluids) are used for dissolving grease, chewing gum, lipstick, and the like. To use, lay the fabric on a pad of folded cloth. Sponge with a cloth dampened with the solvent, using light strokes and working from outside to center of the spot to avoid rings. 2. Bleaches. Chemical bleaches are hydrogen perox ide, 10 per cent acetic acid solution, or house hold bleach. Some stains may be bleached by moistening fabric with lemon juice and salt mixture, drying in the sun. To use a chemical bleach, stretch stained material over bowl of steaming hot water. Moisten stained area with water. Then drop chemical on stain with medicine dropper, let stand a minute. Rinse thoroughly by pouring water through fabric, follow by washing and rinsing thoroughly. Do not allow any bleach to remain in the fabric. 3. Absorbents. Absorbents take up stains like blot ters and do not leave rings, so are best for use 117 on fabrics that waterspot* They’re most effect- | ive on fresh greasy or moist stains. To use an absorbent, such as French chalk or talcum powder,, work powder into stain with fingers, brushing it off as it becomes colored. Repeat until stain is removed. B. A we11-equipped, but inexpensive kit contains the following materials: 1. Dry cleaning fluid (carbon tetrachloride or benzene). 2. Ammonia. 3. Turpentine* ip. Glycerine. 5. Hydrogen peroxide. 6 . Banana oil. 7. French chalk or talcum powder. 8. Denatured alcohol (use one part to one part water). 9. Ten per cent acetic acid solution. 10. Household bleach (follow manufacturer’s directions). 11. Rust remover. Exercises: 1. _ What arethe_ three general classes of stain Il8j I removers? 2. How do you use each type? Problem II: How does one remove specific stains? A. The general rules one must always remember in remov ing stains are these: 1. Treat the stains as soon as possible after they occur. Stains that have dried or have been set by laundering may be very difficult of impossible to remove, 2. Use the mildest treatment first. If the stain is, not greasy, try sponging it with cold ^^rater first' but if the stain contains grease, a dry-cleaning ! fluid or soapsuds may do the trick. Sugary stains are easily removed with clear water. 3. Some stains are combinations of several types so may require several kinds of treatment. B, The specific stains and how they are removed from a) white cottons or linens, b) washable colored or fine fabrics, and c) nonwashable fabrics is now discussed: 1. Blood. a) For fresh stain, soak in warm water. Wash in warm suds. For stubborn stain, use salt water solution (l/i{. cup salt to 2 cups water) and do. not use hot_water_first; it may set_ _ 119! the stain. b) Sponge with warm water. Wash in lukewarm suds. c) Use absorbent first. Then sponge with warm water. 2. Candle wax. a) Scrape off excess wax. Place stained part between blotters and-press with warm iron. Sponge with dry cleaning fluid. b) Same method. c) Same method. 3. Chewing gum. a) Rub with ice and scrape off gum. If stain remains, sponge with dry cleaning fluid. b) Chill with ice and scrape off gtim. Sponge with dry cleaning fluid. c) Sponge with dry cleaning fluid. If sugary stain remains, sponge with water. I j . . Chocolate or cocoa. a) Sponge with liot water. Dip fabric up and down in hot water, then in hot suds. Bleach any remaining stain with household bleach or hydrogen peroxide. Rinse. b) Wash in lukewarm suds. Use dry cleaning fluid to remove any grease spots caused by cream. c) Sponge with dry cleaning fluid, or with dilute alcohol. Cod liver oil. a) For fresh stain, sponge with dry cleaning fluid; then wash in warm suds. Old stains are hard to remove. Bleach with household bleach or hydrogen peroxide. Rinse well. b) Wash in warm suds. Treat old stains with dry cleaning fluid or hydrogen peroxide. c) Sponge with dry cleaning fluid. Coffee or tea. a) Pour boiling water from height of two or three feet through stain. If stain is not removed, bleach with household bleach or hydrogen peroxide. Rinse well. Do not use soap first; it may set the stain. b) Sponge with warm water. If stain remains, apply warm glycerine, let stand one half hour and rinse well. Wash in warm suds. c) Sponge with dry cleaning fluid to remove any grease spot caused by cream; then apply warm glycerine. Sponge with warm water. 121 7. Cream or ice cream. a) Soak in cold water. If ice cream is fruit, berry, or chocolate, treat stain as such. Wash in warm suds. Rinse well. b) Sponge with cold water. Wash in lukewarm suds. c) Sponge with dry cleaning fluid to remove grease. Let dry; then sponge with cold water to remove egg or sugar stains. 8. Egg or meat juice. a) Soak in cold water. Wash in hot suds. Do not use hot water first; it may set the stain. b) Sponge with cold water. Wash in lukewarm suds. c) Sponge with cold water. Let dry. Sponge with dry cleaning fluid. 9. Fruits or fruit juices. a) Pour boiling water from height of two or three feet through stain. If stain is not removed, use household bleach or hydrogen peroxide. Rinse well, and remember not to use soap first because it may set the stain. b) Sponge with cool water. If stain remains, aPply warm glycerine, let stand a few hours, * and rinse well. Wash in warm suds. c) Sponge with cool water; then sponge itfith 10 per cent acetic acid solution. 1 10* Grass. a) Rub with lard or oil and wash in hot suds. Bleach any remaining stain with household bleach or hydrogen peroxide. Rinse well. > b) Wash in lukewarm suds. Treat stubborn , stains with dilute alcohol or hydrogen perox ide. Rinse well. c) Sponge with dry cleaning fluid or dilute alcohol. Test fabric first to be sure solu- tion will not change the color of the fabric. 11. Grease. a) Rub with soap. Wash in hot suds. If stain remains, sponge with dry cleaning fluid. b) Sponge with dry cleaning fluid. Wash in lukewarm suds. c) Sponge with dry cleaning fluid, treat with absorbent, or place stained part between blotters and press with warm'Iron. 12. Ink. a) Soak in cold i^ater. Then apply vinegar or 0 . 2 3 1 » lemon juice. Bleach remaining stains with household bleach or hydrogen peroxide. Rinse; well. If this is unsuccessful, soak in sour milk and wash In hot suds* b) Wash in warm suds. If stain is not removed, treat with hydrogen peroxide. c) Use absorbent, such as cornstarch, French chalk, or talcum powder. Work into moist stain. Shake off as it becomes colored. Continue until stain is removed. 13* Iodine. 1 a) Wash in hot suds, or moisten with water and * expose to sunlight. b) Mash in lukewarm suds. c) Sponge with dilute alcohol. 1 Ip. Iron rust. a) Moisten with lemon juice and salt and dry in the sun. Or, hold stained area over steam ing hot water to which a few drops of ammonia have been added. b) Apply a rust remover, using manufacturer’s directions• c) Same method as above b. IjS# Lipstick or rouge. X2Ld I a) Rub with lard or oil. Wash in hot suds. If , color stain remains, bleach with household bleach or hydrogen peroxide. Do not use soap first; it may set the stain. b) Sponge with dry cleaning fluid. Wash in warm suds. Treat stubborn stains with hydrogen peroxide. c) Sponge with dry cleaning fluid. If stain remains, rub with lard or oil and sponge with dilute alcohol. 16. Mildew. a) Wash in hot suds, moisten with lemon juice and salt, and dry in the sun. If stain is old, bleach with household bleach or hydrogen peroxide. Rinse well. b) If stain is fresh, wash in warm suds. Old stains are difficult to remove. c) No satisfactory method. 17. Nail polish. a) Sponge with nail polish remover. Wash in hot suds. Remove any remaining color with house hold bleach or hydrogen peroxide. Rinse well. b) Same method, except for acetate. Sponge acetate fabrics with dry cleaning fluid, ■ apply a drop of banana oil, and remove dis- ; solved polish with cloth, c) Sponge all fabrics, except acetate rayon, with nail polish remover. Sponge acetate rayon with dry cleaning fluid, apply drop of banana oil, and remove dissolved polish with cloth. 18. Paint. a) Scrape off fresh paint and wash in warm suds. If stain has dried, soften first with lard or oil; then sponge with turpentine or banana oil. Wash In warm suds. b) Same method. c) Scrape off fresh paint and sponge x^Ith dry cleaning fluid or banana oil. If paint is hardened, apply solvent on both sides of fabric. 19. Perspiration. a) Wash in hot suds. Rinse. Bleach in sun. If stain remains, use household bleach or hydro gen peroxide. b) launder in warm suds. Rinse well, c) Sponge with 10 per cent acetic acid solution. 126 20. Scorch. a) Moisten and expose to sunlight. Repeat sev eral times. Bleach with household bleach or hydrogen peroxide, if necessary. Rinse well. b) Can seldom be removed. Brushing with emery board may improve woolens, however. c) Can seldom be removed. Brushing with emery board may improve x^oolens, however. 21. Wine. a) Identical method for removing fruit stains. b) Identical method for removing fruit stains. c) Identical method for removing fruit stains. Exercises: 1. How do spotting agents remove spots? 2. What stains can be removed by carbon tetrachlor ide? 3. What stains are best removed by water? I | _ . How can you prevent the formation of rings in removing spots? 5. How are ink stains best removed? 6. What purpose does hydrogen peroxide serve in removing stains? Extra problems; Make a ,fstain removing1 1 • chart showing all the general stains and the best method of removing each from different materials. Take scraps of material and "stain” with differ ent stains. Remove the stain. unit vii THE CHEMISTRY OF SANITATION IN THE HOME Science has taught people the necessity of disposing of the waste materials of the home, of keeping the homes well lighted and well ventilated, and of keeping the fur nishings free from dirt. The chemist has provided us with many materials, such as soaps, bleaches, disinfectants, oils, waxes, and polishes, for use In maintaining a clean, healthy home. Purposes: The purposes to be achieved In this unit are the following: 1. To discover the part that chemistry plays in making sanitary homes. 2. To learn the best ways of maintaining sanitation in the home. 3. To help you to select the proper and most econ omical cleaning materials. I 4-. To learn how to combat Insects and rodents which may invade the home. 5* To aid one in selecting the materials for a good home medicine cabinet. Problems: The problem to be solved in this unit are: _1. Mia.t-are _the chemicals used in laundering, and how are they made and used? 2 . How should walls, woodwork, and windows be clean-’ ed? 3# What are the sanitary methods or waste disposal in the home ? I j . * How should the plumbing of the home be cared for? "What should a good home medicine cabinet contain? 6. How may the home be kept free of rodents and insects ? Word list; Esters: a compound formed by the reaction between an; acid and an alcohol with the elimination of ! a molecule of water. Rodent: a mammal belonging to the order of gnawing or nibbling kind that includes the mice, squirrels, and the like. Problem I: What are the chemicals used in laundering, and i how are they made and vised? A. Soaps are compounds formed by the reaction of bases with fats, chemically known as fatty acid esters. The three most important fatty acid esters are: palmitin, stearin, and olein. They are found in lard as well as in tallow, olive oil, cottonseed oil, and 130 i other animal and vegetable fats or oils. : 1. The choice of fats or oils for soapmaking is determined partly by the cost of the materials. Pew soaps are made from one fat only. 2. The large-scale manufacture of soap was not possible until the discovery of practical methods of manufacturing alkalies on a large scale. B. The process of soap-making is basically the same technique of all various manufactures. Each product, however, is a different result having its own desired advantages. 1. Regular soap is made in this general manner: a) The ingredients used in the manufacture of soap are measured out in exact amounts before being poured in the soap kettles. The making of soap is an exact chemical process. b) The materials are cooked for two days in large soap kettles, heated by steam pipes, where the fats and oils combine with the sodium hydroxide to form the new substances soap and glycerin. The soap kettles are three stories high. c) The soap is separated from the glycerin, excess chemicals, and water by the addition 131| t of salt. After this process the soap flows \ to flat iron frames, where it cools and solidifies. The large frames of soap are then cut into bars by means of taut piano wires, and the rough cakes are ready to be molded, stamped with the manufacturer’s name, and wrapped ready for shipment* 2 * If milled soap is desired, semisolid soap is i rolled to a thin film, dropped off the rolls in ribbons, squeezed into pellets, mixed with per fume, compressed to a hard bar, cut, shaped, and - wrapped ready for shipment. ! 3* For flake soap, the semiliquid soap runs into a 1 trough, where a chilled roller picks up a thin film, which hardens. A large blade cuts thin ribbons of soap from these rollers. I f . * Powdered soap is made by squirting the molten soap from a nozzle as a spray into hot air. 5# Soft or liquid soaps are made by using potassium hydroxide instead of lye* These are often used in making shampoo soaps and in soap-dispensers. The glycerin formed remains in the soft soap but adds no value to the soap. 6. Rosin, although not a fatty acid, reacts with lye 132 to form a sodium, salt which resembles soap in many respects. a) It is soluble and has a high frothing power; for these reasons it is added to many laundry soaps. b) Soaps containing rosin are yellow in color and form suds rather easily. c) The cleansing power of rosin soaps is much lower than that of ordinary soap, and the presence of rosin in any quantity is undesir able. If soap contains more than 15 per cent rosin, It is known as a low-grade soap. d) If the water in which the clothes are washed ’ is hard, there Is danger that curds will form from rosin soaps and discolor the clothes. 7. Soap powders are not to be confused with powdered soap, which is merely soap in powdered form. a) Most soap powders are mixtures of soap and alkali substances known as builders, such as sodium carbonate, trisodium phosphate, borax, . and sodium sulfite. Sodium carbonate is most frequently used. b) Some washing powders also contain a bleaching agent, such as sodium perborate. These X33| usually are called oxygen washers and often contain part of the word noxygent ! in the com mercial • name. As a rule, the cheaper the washing powder, the larger the proportion of alkali present. The builder is added to help to soften hard water and to act as a cheap detergent, or cleansing agent. It should be I remembered, however, that the builder is a less efficient cleansing agent than soap* Soap solutions owe their cleansing power to two conditions: a) The ease with which they wet dirty clothing, dishes, equipment, and the like; and b) the fact that they form emulsions with grease and prevent its return to the articles being washed. (1) Soapy water penetrates and spreads over the surface of immersed articles much more readily than plain water; thus its wetting power is greater. (2) Pure water will not dissolve grease, but soapy water forms an emulsion with grease, oil, or sugars, (3) When dirt which is present in a film of 13 1 -1 -1 grease and oil adheres to an article, it is removed as the grease and oil are emulsified by the soap, (li) As long as there are suds in the water, the dirt and grease are held in suspen sion, If the suds break, the dirt and grease are precipitated upon the cloth ing again. Hence clothes should be re- ■ moved from the water and rinsed before the suds disappear, (5) Soaps lather more freely in warm or hot water. Also, fats melt at temperatures ! slightly above body temperature. There fore, warm soapy water possesses a greater cleansing, or detergent, power than soapy cold water, C. The detergents, often called nsynthetic soaps,11 have become increasingly important to the consumer since World War II, Detergents serve the purposes of soaps but are really not soaps at all. They act similarly to soaps by lowering surface tension; they are not inactivated by calcium and magnesium, however, and are therefore equally effective in hard or soft water at all times. This is not true of ordinary soap. 1# Chemically, the detergent products are made by treating lauryl alcohol with sulfuric acid and sodium hydroxide, which results in a compound known as sodium lauryl sulfate. Lauryl alcohol is one of the higher alcohols, produced by hydro genating the fatty acids obtained from vegetable oils. 2. There are various qualities of synthetic deter gents on the market. Each manufacturer stresses its own selling points. Thus, one finds some brands better for the hands, others better for i dishes, and the like. Detergents can be manu factured in granular, flake, and liquid forms. Some types can be made into cakes. 3. Detergents are effective.on woolens and have excellent grease removing properties but do not remove all stains. l | _ . The market is expanding as each year passes because since the advantages out-weigh the dis advantages, this makes a good selling factor. Between five and six hundred detergents are available commercially. D. Bluing is used to counteract the yellow or dingy colcr in clothes caused by careless rinsing or by lack of 136i sim-light* Bluing may be bought in paste, liquid, or; solid form. 1. Ultramarine blue occurs naturally in the mineral form and may be manufactured by heating a mix ture of kaolin, sodium carbonate, or sodium sulfate, sulfur, and carbon. 2. Aniline blue, a coal-tar prodiict, is sold in the crystal, liquid, or powder form. It is probably the best kind to buy for general laundry purposes. 3. Pnussian blue, or ferric ferrocyanide, contains ; iron which, when this bluing is used with clothes! I from which the soap has not been thoroughly rinsed, may react with the alkali of the soap to form iron oxide. This iron oxide may be deposit ed as spots or streaks on the clothing. Bluing should be added to the last rinse water In sufficient quantity to give the water a clear blue color. E. Starch is used in laundering. One has learned that starch is a carbohydrate obtained from many vege tables. It Is secured principally from such grains as corn, wheat., and rice, though some is obtained from potatoes. The chief difference In the starch 137 from each, of these sources lies in the fact that ' the starch grains, or particles, are of different1 sizes. Gornstarch is used more often in launder ing, though wheat starch will give a softer fin ish, and rice starch is sometimes used for very fine fabrics. A good deal of the starch on the market for laundering is a blend of different starches. 1. In preparing starch for laundry purposes, cold water is added first to separate the granules, after which boiling water Is added. , The mixture may be boiled gently for five or ; i ten minutes and strained through a clean | cloth to remove lumps. White fabrics are usually dipped in this solution while it is still hot. Bluing is sometimes added to give it a slight blue tint. 2. The garments are usually dipped in the starch both immediately after having been wrung free of the rinse water. They should be turned wrong side out before being dipped in the' starch. All the starch solution possible should be wrung from the goods. 3* Uncooked, or cold, starch solution Is 1 3 8 1 I sometimes used on the cuffs, collars, or other parts of garments requiring a stiff starchy finish. When the cuff or collar is ironed, the starch is cooked by the hot iron. 1 | . * Starch is used to produce a smooth attractive finish to goods when they are ironed. It also adds body to a garment, filling the spaces be tween the fibers, thus helping to prevent dirt from adhering to the material. Most cotton goods, contain starch as a filler when purchased. This is soon washed out by continued laundering. The ' starching of goods helps to replace this filler* ; P. Bleach Is used liberally in most homes. The most familiar bleaches used in the home are those made from chlorine. Chemically, these substances are essentially a sodium hypochlorite solution. This solution may be prepared by passing chlorine gas into 1 lye or by the electrolysis of a brine solution. The commercial grades run from i f . per cent to 6 per cent hypochlorite by weight. 1. There is little difference in the various brands on the market. The thrifty housewife will com pare the cost of the various brands with the per cent of hypochlorite as shown on the label of the 139j bottle* i 2 . Javelle water may be prepared from chlorinated lime, a white powder which is sold in most gro cery stores. This bleach is prepared by stirring the powder in water and allowing the insoluble lime to settle to the bottom. 3. The bleaching action of sodium hypochlorite is not due directly to the chlorine, as might be thought. Sodium hypochlorite is rather unstable and gives up an atom of nascent oxygen readily. The bleaching action is one of oxidation. The nascent oxygen oxidizes the dingy, yellow color ing substances, thus making the clothing clean and white. It. Sodium hypochlorite may be added to the first rinse water, about one tablespoonful to each gallon of water. It is used with white cotton goods as a bleach. Colored clothes may be rinsed, in this water if the colors are fast. This chem ical may also be used as a stain-remover and as a household disinfectant. Bleaches should be used cautiously, at low temperatures, and never with silk, wool, synthetic fabrics, or leather. Exercises: 1# Name four kinds of fats or oils from which soap may be made ♦ 2 * Hox^r do. soaps made from fat and potassium hydro xide differ in texture from those made from fat and sodium hydroxide? 3* Why is rosin added to some laundry soaps? i f . * What is the difference between powdered soap and washing powder? * 5* Why does hard water have no effect on soapless soaps? 6 . Explain how soap helps to clean clothes, 7. Explain why bluing is used in washing white goods. 8. Explain the bleaching action of sodium hypo chlorite. Problem II: How should walls, woodwork, and windows be cleaned? A. Cleaning painted surfaces.' 1. Enamel-painted walls and woodwork, such as are found in many bathrooms, should be wiped fre quently with a wall brush or with a clean dry flannel cloth tied over a broom. 2. Occasionally the woodwork may be washed with warm soapy water, rinsed, and wiped dry with clean _ lij.ll I cloths. The soap should be a white neutral soap or soap powder. 3. To prevent streaking, the rinse water should be changed frequently, and plenty of clean washrags should be used. Care should be used to remove all soap, as it might react with the paint if left to dry in contact with it.-' Ip. If the woodwork is painted with a dull-finish paint, more care must be exercised, as there is a, greater tendency for some soap to remain on the painted surface* White bar soap is better to use, in this case because there is less danger of small undissolved particles remaining in the water, which might adhere to the paint. A little household ammonia (ammonium hydroxide) may be added to the water. 5. Many of the commercial wall-cleaners contain trisodium phosphate. These preparations are usually good cleansers, but if too strong a sol ution is used, there is danger of removing some of the paint. B. Cleaning varnished or oiled surfaces. 1. Varnished or oiled wood may be cleaned occasion ally with a clean cloth moistened with linseed oil, turpentine, kerosene, or furniture oil. In general, shellacked wood should never be washed with water, but varnished wood may be if care is used to wipe it dry afterward. Varnished hardwood floors may be cleaned with an oil mop or cloth. Oil for this purpose may be purchased In jars, bottles, or cans at grocery, department, or hardware stores. It Is usually a petroleum derivative, colored and sometimes scented. A good economical floor oil may be pre pared by dissolving a quarter-pound of paraffin wax in a quart of kerosene. Some hardware mer chants keep this mixed for customers as paraffin floor oil. After wiping floors with such an oil, It is wise to go over the surface again with a clean dry cotton cloth for polishing. When hardwood floors are waxed, excessive amounts of oil should not be used In cleaning, because the oil will tend to dissolve and remove the wax. Linoleum may be mopped or i^ashed with clear warm water• Soapy water should be used only occasion ally when the floor is rather dirty, as the a3.ka- li of the soap may attack' the colors of the linoleum If left in contact with the linoleum too 343 long. The floor should always be rinsed with : clear warm water after using soap. Wax is often ; used on linoleum, the best type being a water- soluble wax. A mop containing a slight amount of oil may be run over the floor daily to brush away the dirt which clings to the surface. 5* Wallpaper-cleaners are on the market which are i * plastic in nature. They sometimes contain a gum,! such as gum tragaeanth. Win d ow-c1e aning. 1 . The cloth used for cleaning and polishing win dows, mirrors, and other glass surfaces is of the' utmost importance. Care must be exercised to use, one which will not leave lint on the surface. 2. The water used should be clear. Ho soap should be used, as this leaves a film after drying. A little household ammonia added to the water is effective in cutting any grease particles which may be on the surface# 3. Professional window-cleaners generally use tri- sodium phosphate dissolved in water. A teaspoon ful of the poitfder in a gallon of water is usually sufficient. Ip. Bubbing alcohol mixed with an equal amount of water is effective in washing windows. A few drops_of kerosene on a clean cloth may also be used to wipe windows free of dirt* 5* There are a number of commercial window-cleaners on the market. Some of these contain ethylene glycol, and others are essentially alcohol, glycerin, or a kerosene-water emulsion. They may be applied as a spray and wiped clean with a cloth. If a lintless cloth is not available, a piece of newspaper does an excellent wiping Job. Exercises: 1* Why should walls which have been washed with soapy water be rinsed off well? .2. What are two other substances other than soap which may be used in washing woodwork? 3* Why should not soap be used In washing windows? Problem 111: What are the sanitary methods of x*raste dis posal in the home? A, Keep the garbage pail clean. Perhaps the most neg lected utensil in the modern home is the garbage pail. The food refuse and the warm, moist, dark atmosphere of the garbage pail are both ideal for the growth of germs. 1* The unsightly cans are the breeding places of millions of flies in many cities; hence they should be cleaned daily. A good practice is to sprinkle a little chlorinated lime on the bottom of the cans to prevent flies from depositing eggs there. 2. A little sodium hypochlorite, about three table spoonfuls to each quart of warm water, is a good disinfectant for garbage cans. It should be washed around the sides and rim of the can and allowed to stand in the can for five or ten minutes. The can should then be rinsed and dried. Use the garbage disposal unit. The best method of garbage disposal is to use an electric grinder, also known as the garbage disposal unit, which disposes of the garbage by grinding it into small particles, which may then go out of the house as sewage. Many types can be found in the market at different price ranges. Dispense with empty tin cans properly. Empty tin cans should never be allowed to collect out of doors. The practice of putting them in a box in a corner of 3461 I the yard or of throwing them on ash pits is a care less practice. Rainwater often collects in such cans which, is a perfect breeding place for mosquitoes. Plies also find this' happy breeding ground, D. The sanitary neighborhood is one which gives careful consideration to the collection of the garbage and other refuse of its citizens. Every citizen owes it to his neighborhood to see that his premises are kept neat and sanitary. Exercises: 1. Explain how the garbage pail which is kept in thej I house, usually in the kitchen, may be kept in a sanitary condition. 2. What chemicals may be used to disinfect garbage pails ? 3. Explain why most of the flies and mosquitoes in cities may be traced to improper garbage dispos al. L. How do cities protect their citizens in regard to. garbage disposal? Can you suggest ways in which your city could be of more service to its citizens in this matter? Problem IV; Hoitf would the household care for the plumbing l i j - 7 of the home and how should it be done? : A. Each member of the household should be familiar with the shutoff valves of the water system in the home, so that in case of excessive leakage or the bursting of pipes the water may be shut off until repairs can be made. These valves should bear a tag stating their use or function. All the faucets in the house should be opened as soon as the main shutoff valve is. closed so that a t ! blow out! f will not occur due to a vacuum. i B. Water traps are in reality water seals which prevent obnoxious gases of the sewer from entering the house.> i C. The cleaning of the traps is most important for a household member to know among anything else. When a water trap becomes clogged and the water will not run out, a soft-rubber-cup plunger may be placed over the opening and the piunger worked up and down. 1. The trap under the kitchen sink is likely to clog with hardened grease. At the bottom of the trap is a clean-out plug. A bucket may be placed under this trap, the plug removed, and the grease of solids removed with a wire. It is a good plan, however, to allow boiling water to run through the sink every few days to melt and : 1^8] remove this grease before it becomes troublesome. If this does not work, potash lye dissolved in boiling water may be poured down the sink. The lye reacts with the grease to form a soluble liquid soap. 2. Some commercial drain-cleaners contain lye and small, pieces of aluminum. The aluminum reacts with the sodium hydroxide when mixed with water to form hydrogen gas. The churning action of the escaping gas aids in loosening the grease, making it possible for the lye to act upon the grease. The objectionable odor and the fine mistlike 1 spray of lye solution which Is given off when a Gleaner of this type Is used are disadvantages of this drain-cleaner. Exercises: 1. Is there a place where the water coming Into your home may be turned on and off? 2. Why Is aluminum added to commercial drain- cleaners ? 3. Why is it a good practice to pour boiling water down sink drains occasionally? Problem V: What should a good home medicine cabinet 1 1 4 - 9 contain? A* The home medicine cabinet is usually placed in the bathroom and is filled with all sorts of odds and ends. It should be arranged neatly and every item properly marked so that there could be no mistake In identifying an article. B, A valuable pamphlet entitled The Home Medicine Cabinet may be obtained by writing to the United States Department of Labor, Washington, D. C. This explains the importance of having certain articles in the home at all times. C. A basic home medicine cabinet should include articles such as the following: 1. Antiseptics for cuts and scratches. Tincture .of iodine and rubbing alcohol. 2. Burn preparations (tannic acid powder, picric acid gauze or nAmertanTf). 3# Pain-reliever. Aspirin or ^Emplrin.1 1 I 4. Laxative, such as milk of magnesia or mineral oil. 5. Emetic to produce vomiting. Sirup of ipecac. 6. Stimulant for use in shock or fainting. Aromatic spirit of ammonia. 7.- Sterile bandages and gauze. Various sizes in sterile containers. 8 . Absorbent sterile cotton. 9. Adhesive tape. 10. Applicator sticks in a tube. 11. Clinical thermometer. 1 2. Hot-water bottle. 13. Saturated solution of boric acid. 14. Pair of scissors. 15. Pair of tweezers. 16. Sodium bicarbonate. 17. Medicine-dropper. 18. First-Aid book. D. Ihe location of the medicine cabinet should be out of reach of the children. All bottles should be well corked and labeled. Empty bottles and long-unused medicines should be discarded. Exercises: 1 . Give illustrations of how each of the articles contained in a well-equipped medicine cabinet may be used. 2 • Explain how a clinical thermometer should be used and taken care of. 3. Needles are sometimes used in removing splinters. Explain how you would disinfect, or sterilize, a needle before using it on a wound, k. Why should empty bottles and long-unused medicine bottles be disposed of? Problem VI: How may the home be kept free of rodents and insects ? A. Control of insects by temperature. Almost all house hold insects become inactive at temperatures below h0° P. At temperatures of 10° F and lower most insects die, High temperature of 120° P or more will kill all insects and their eggs. The exposure of infested articles to the direct rays of the sun in ■ summer will also aid in ridding them of insects. B. Control of insects by other methods. The eradication of insects by the use of poisonous gases is effective although dangerous for an inexperienced person to use. 1. The most effective fumigant is hydrogen cyanide, or hydrocyanic acid gas. It is a deadly poison and should be used only by competent professional exterminators. 2. Sulfur fumes created by the burning of sulfur in rooms are sometimes used. C. Ants. The secret of eradicating ants lies in finding their, nest', and .killing the queen and the young. Sodium fluoride powder is an effective poison. D. Bedbugs. Bedbugs lay their eggs in cracks of floor- ' ing and furniture. They are found in the tufts of mattresses and around bedsprings. Vacuum cleaner, kerosene, or fumigation will kill them. E, Gockroaches. These are often found around the base of kitchen sinks, in pantries, under cupboards, and baseboards, and in basements. Sodium fluoride should be dusted around those areas. P. Crickets. These are most effectively destroyed by the use of pyre thrum powder blown under furniture and, sinks and in pantries. G. Carpet beetles. These infest the floor coverings and| can be removed by the vacuum cleaner or kerosene. H. Pleas. Spread naphthalene or paradicklorobenzene all over the floor, then close doors and windows. I. Pood weevils. These infest such dry foods as meal, flour, and cereals; these foods should be burned. J. Houseflies. Flypaper, formalin solution, and commer cial fly sprays are good sources of destroying and killing flies. K. Mosquitoes. Water left standing in pools may contain thousands of mosquito larvae. A pyrethrum-kerosene spray and citronella oil rubbed on the body are two 153 repellents. L. Moths* The two best and least expensive chemicals used to destroy moths are naphthalene and paradich- lorobenzene * M. Rats and mice. The snap trap is the best article used because one knows when the mammal has been caught. Rat poisons contain thallium, arsenic, and other poisonous chemicals, N, Wood ticks. These are more common in wooded areas. Put a drop of turpentine or benzine on the flesh where the tick might be. 0. Termites. Keep the wood dry, have good construction, and soak the ground with crude orthodiehlorobenzene solution. Exercises: 1. Make a list of diseases which may be spread by various insects. 2. Make a list of common insects and beside each write a short statement about how to eradicate it. 3# What can each family do to help to reduce flies and mosquitoes in the neighborhood? Extra problems: i 5 b \ 1. Outline a plan for making a home sanitary. 2. What chemicals are used in your home to make it j sanitary? State their composition and their use., 3. What are the compositions of the various brands of rat and rodent poisons sold in your town? k. How do electric garbage-disposal appliances work? What are their advantages and disadvantages? 5. Make a list of the contents of your home medicine‘ cabinet. What use is made of each item? What is the chemical composition of each medicine? 6. What problems of sanitation are peculiar to mountain or seashore cabins? How is each problem taken care of? ! 7. How is chlorinated lime used in making out-houses more sanitary? 8. What are the best methods for cleaning rugs, carnets, and unholstered furniture? u J J.. 9. What are the most acceptable methods to use and what chemistry is involved in the washing of dishes ? 10. What sanitary measures should be taken when per sons in the home are ill? xnsriT v i i i THE CHEMISTRY OP HOME DECORAT I OHS Most people spend a great deal of time in the home. It is a place that most of us enjoy and refer to with a great deal of pride. Science has done much to make our homes more enjoyable places in which to live. Paints, varnishes, and lacquers have added more to the attractive ness and cheerfulness of our homes than most people realize. Paints, for example, are available in a wide range of colors from deep tones to beautiful pastels as well as wallpapers, so that any color combination in decorating is possible. Purposes: The purposes to be achieved in this unit are as follows: 1. To learn the principles involved in successful and artistic decoration. 2. To discover the best uses of decorative materials and how to select the best ones. 3* To determine the relative merits of various decorative materials. 1 | . . To realize the Importance of harmony and taste in home decorations. Problems: The problems to be solved In this unit are: 1. Why should decorative materials be used in the home. 2 . What are paints, enamels, varnishes, lacquers, and other decorative materials composed of, and how are they made? 3. How may home-decorating be done successfully? Ip. What factors should be taken into consideration in purchasing decorative materials? Word list; Pigment: a coloring matter or substance. Problem I: Why should decorative materials be used in the home ? A. The term "decorative materials" in this unit is used to refer to paints, enamels, lacquers, varnishes, stains, and wallpaper. B. These decorative materials are used in the home for the following reasons: 1. Protection and preservation. Any materials used in constructing or furnishing a home will decay or corrode if exposed to the air without protec tion. Decay or rusting is usually caused by oxygen though it may be hastened by moisture, gases, and certain organisms usually found in the air. When paint or any other related product is 1^7 j I placed upon wood, Iron, or other materials, it seals the pores, so that the gases and organisms which cause destructive materials protect and preserve the home. Economically, houses that are not painted depreciate rapidly in value, while those which are decorated periodically are much more desirable and more salable, 2. Appearance. Most people are interested in beau- ' tifying their homes. The use of paints, enamels, varnishes, lacquers, and wallpapers has much to contribute to the appearance of the home. In fact, the home would be a rather shabby place without these materials. Beautiful, harmonizing ; colors add much to the livability of a home. Proper color combinations have much to offer in making a home bright, tasteful, and attractive. 3. Sanitation. Wood and metal surfaces contain pores which have a tendency to catch dirt, grease and germs. If these surfaces are painted, the pores are closed, and a much more sanitary condi tion exists. In addition, painted surfaces may be cleaned frequently without hastening the decay or rusting of the wood or metal. Exercises: 1* Why have paints improved, in quality in the past? 2. List the decorative materials used in home decor ation. Describe them. 3. How does paint protect a surface? !p. Explain the statement "Save the surface, and you same all*” 5. Give two reasons for painting houses. Problem II: What are paints, enamels, varnishes, lacquers, and other decorative materials composed of, and how are they made ? A. Paint. Most' paints consist of a pigment, an oil, a thinner, and a drier. 1. Pigment. Pigment gives body to a paint, and it also gives color to it. The most important pig ments used are white lead, zinc white, titanium oxide, and lithopone. a) White lead pigment paint. The Dutch process is most commonly used in manufacturing white lead. In this process lead is placed above acetic acid or vinegar so that the fumes of the acid attack the lead, changing it to lead acetate. Heat is produced by placing fer menting tanbark on top of the earthenware pots_containing_the acetic acid and lead*__ i 5 s j The decomposition of the tanbark supplies carbon dioxide, which reacts with the lead acetate to form basic lead carbonate. -White lead makes a paint that is easy to.brush and ' one that has excellent covering power. b) Zinc white pigment paint. This is made by- heating zinc in the presence of air. The zinc reacts with the oxygen to form zinc oxide. This pigment is whiter' 'than white lead but it does not have as great a covering i power. Paint made from zinc white makes a harder surface than that made from white lead, but it tends to flake and crack as it ages. Correct mixtures of white lead and zinc white seem to be the best base, or pig ment, for paint. c) Titanium oxide pigment paint. This has several times the covering power of white lead. It Is rather expensive and is general ly used with white lead in the manufacture of* paint. d) LIthopone pigment paint. This is made by heating zinc sulfate and barium sulfide, which results in the formation of mixture of 1601 zinc sulfide and barium sulfate. Lithopone produces an excellent white color and has good covering power. Because it discolors in sun-light, it is used in making interior paints. 2. Adulterants. As a rule, cheap pigment materials greatly reduce the covering power and result in a paint which is hard to apply and which is not durable after being applied. The most common adulterants used are barium sulfate, silica, gypsum, and calcium carbonate. 3* Oil* In addition to acting as a suspending medium for the pigment, an oil should form a hard protective coat when it dries. The oil which most successfully meets these requirements is linseed oil. It is the most common vehicle used in paint and is obtained from-flaxseed. When linseed oil is exposed to the air, it reacts with the oxygen, forming a tough, horny substance. I } . . Thinner. A mixture of lead and oil is too thick to be applied with a brush. The addition of a thinner dilutes this mixture so that the paint becomes smooth and easy to work, and penetrates more readily. The thinner also causes more rapid drying and hardening of the paint. The best and most widely used thinner is turpentine. This product is obtained by distilling the sap of the pine tree. Frequently, inexpensive adulterant thinners are used in place of turpentine. Such adulterants as naphtha and benzene impair the quality of paint. 5. Drier. Without the addition of a drier, the average paint would take from two to three days to dry. With the addition of a drier, this time ■ - can be shortened to as little as four hours. i Most driers are mixtures of compounds of lead and manganese; red lead and manganese dioxide are commonly used. 6. Color. A paint made with the ingredients here tofore mentioned are white in color. If any other color is desired, color pigments must be added. Various chemicals produce different color combinations; these will not be mentioned here. B. Varnish. There are two types of varnishes. 1. Spirit varnish. This is made by dissolving a resin or gum in alcohol. The most commonly used varnish of this type is shellac. When shellac is applied to wood, the alcohol evaporates, leaving 162| ! the opigihal resinous gum, A shellac surface is not as durable as that made by oil varnish, 2. Oil varnish. This is made by dissolving gum or resin in linseed oil which is also the best grade. To make the varnish flow more freely, turpentine is usually added* The oxidation and drying of the gum and oil produces a hard, dura ble surface. Cheap varnish can be made from resins of a poor quality. 3* Enamels. An enamel is a varnish to which a pig ment has been added. The pigment is usually the same as is used in house paint: white lead, zinc oxide, or titanium oxide. Because enamel can be ; used for inside work only, lithopone is sometimes used as the pigment. Such an enamel is inexpen sive, but the quality is not the best. Enamel differs from paint in that, when it dries, it shows no brush marks. If. Lacquers. A lacquer is a solution of cellulose nitrate compounds. The low-nitrated cellulose is mixed with (1) a resin, such as is used in var nish; (2) a plasticizer, usually an oil, to pre- vent cracking; (3) an organic solvent, such as amyl acetate, or banana oil; and ( ) _ j . ) a color. Such a mixture produces the modern type of lac quer, Because lacquers dry very rapidly, they must be applied carefully. The applied lacquer cannot be brushed repeatedly but must be "flowed” on. The best lacquering is done with a spray gun. Lacquer produces a hard surface which will withstand weathering. Articles painted with it can be used within a few hours after painting. Stains. There are two. kinds of stains. a) Oil stain. This is a paint diluted with a thinner, such as turpentine; and if the coloring is added in proper amounts, it may be used to imitate any kind of wood* Oak, walnut, and mahogany oil stains are usually permanent and effective. b) Dye stains are usually solutions of coal-tar dye. They are not as practical for home use as the oil stains. Linoleum and oilcloth. These two products are closely related to paint in that they are made from linseed oil and from pigments and driers of the same type as those used in paint. Linseed oil, pigment, and cork dust are sprayed onto can vas, felt, or burlap and allowed to dry in layers 1 6 1 | . until a thickness of about one inch is attained. The raw linoleum is then passed through heated rollers, and one gets the finished product, in laid linoleum. When colored designs are desired, blocks of the raw linoleum of different colors are fitted together before the heat treatment is applied. Cheap linoleums are usually thin and have the designs printed on the surface. Oilcloth is made by painting pigmented linseed oil on thin fabric. It is then heated and decorated by printing. 7. Wallpaper. Many people prefer wallpaper rather ' l than paint for interior wall decoration. It Is now possible to obtain wallpaper which Is prac tically colorfast, or lightfast. It is also possible to obtain washable wallpaper, from which almost any stain or spot can be removed with soap and water. Wallpaper is made by painting one side of the paper with a first, or ground, coat, which is composed of pure clay mixed with a pig ment and a binder. In the better grades of paper the binder Is casein; in the cheaper grades it Is glue. A color is added to give the paper an overall, or base color. The paper is then ready 165 ; for the printing of the colored design. The de- ' sign is carved on wooden rolls, one for each color used, and the paper is printed with the design. To make wallpaper washable, it is spray ed with a mixture of chemicals after the printing process. The ingredient of these sprays are not divulged by wallpaper companies. It is known that formaldehyde is one of the principal chem icals used. Exercises: 1. What is the compostion of paint? 2. What is the advantage of zinc white over white lead as a paint pigment? 3. What adulterants are sometimes added to paint? Ip. What effect do adulterants have on the paint? 5. What substances may be used as vehicles in the making of paint? Which ones are considered the best? 6. How does a drier make paint become dry more rapidly? 7. What Is turpentine? 8. List and describe six different color pigments. 9. How are oil and dye stains made? _ . . 10.. J2esjsrjLbe jbhe ..differences between varnish, enamel,.. l66j and lacquer, 11* Describe the processes involved in making lino leum.* How does inlaid linoleum differ from printed linoleum? 12. How is wallpaper manufactured? 13* How is wallpaper made washable? Problem IIX: How may home-decorating be done successfully? ( A. The hanging of wallpaper and the application of paints, varnishes, enamels, and lacquers require much . skill. For these reasons, one can be more certain that the work will be satisfactory if it is done by a 1 competent, skilled decorator than if you try to do it 1 yourself. Many homeowners enjoy planning and doing the job of decorating the home. For some, this activity is a hobby and for others, it is a way of making the home attractive x^rithout great expense. B. The exact process of painting will not be discussed here because all paints have their own directions. However, the general rules should be briefly listed. 1. The surface should be clean, free from dirt and grease. 2. The surface should be smooth. 3. The surface should be dry before applying any paint. ____ ! { . . Use good quality of paint. 5. Use the correct size of brush, and use a good brush rather than a cheap one. 6. Brushes should be cared for with great import ance . 7* Take every precaution against lead poisoning. C. Color selection for home decoration is of great importance in making the home livable and attractive. It demands careful consideration. The selection of colors necessitates careful study of the likes and dislikes of every member of the family. It also requires knowledge of what constitutes harmony be tween the colors Of furnishings and those of decora tions, as well as what color combinations will "bring out’ 1 the most that Is possible in a home. Exercises; 1. Is it advisable to do your own home-decorating? Why or why not? 2. How should the surface be prepared for painting? 3. What precautions should be observed In using paint? Problem IV: What factors should be taken Into consideration In purchasing decorative materials? 168 i A. Good workmanship is essential, When painting is being done by a skilled, or master, painter, the cost’ of the labor is generally about twice that of the paint. Therefore, it is uneconomical to use an inferior quality of paint. As a rule, those mater ials which are priced low are inferior in quality. B* Buy quality materials. Hot only should the paint be of good quality but everything else including the brush. If one wants to mix his own paints, the best of materials should be used. It is not advisable for one to make all of his own paints or lacquers, C. A decorated surface can be refinished. If a repaint , job is being done, it' is essential that the new paint, varnish, or enamel adhere to and bind with the old. Experience has taught experts that the new decorative materials must be made of the same kind and quality of ingredients as the old if the proper sealing is to take place. It is not uncommon for varnish which is used to cover an already varnished floor to scar and crack easily. This is generally because the new varnish is a different kind from the old, D. If you do not do your own decorating, it is essential that you use great care In selecting a decorator. 169 | i Select one who has some artistic sense* Such a work- : I man can often make suggestions and plan his job so that a much more pleasing appearance will result. Exercises s 1. How often should a house be repainted? 2. What are the differences between poor-quality paints and good-quality paints? 3. How should a previously decorated surface be refinished? Extra problems: 1. Where are the resins used in varnishes obtained? What is their chemical nature? 2. Make a survey of your home and determine the kinds of materials needed and their cost of application. 3. Visit an interior decorator and get the latest information regarding color harmony in the home. k. What are the best methods of surfacing the different types of flooring? APPENDIX EXERCISES FOR UUIT I Some of the statements which follow are true, and some are false* On a separate sheet of paper write- the word TRUE for those which are true and the word FALSE for those which are false* Bo nothing for those about which you are doubtful. Rewrite the false statements so that they are true • 1* Cooking is a modern art. 2. The cooking of food is an art. 3. The cooking of food destroys the food nutrients. L | _ . Chemical changes occur when food is cooked. 5. All uncooked food is less nutritious than cooked food. 6. The digestibility of food is increased through cooking. 7. Cooking destroys harmTul germs in food. 8. Trichina is a parasite which sometimes infests beef. 9. Rare Hamburger is a healthful food. 10. It Is impossible to overcook food. 11. The starch In uncooked starchy vegetables, such as potatoes, is easily digested. j 12. Pork should be thoroughly cooked before being eaten. 13. Vegetables become harder in texture when cooked, lip. Most vegetables contain all the food nutrients. 15. Starches and sugars in vegetables are easily lost in cooking. 16. All methods of cooking preserve the vitamins in vege tables. 17. Vegetables should be covered with x^ater xVhen they are cooked by boiling. 18. Some vegetables contain proteins. 19. Some proteins are coagulated when heated, whereas others are made soluble by the same treatment. 20. One purpose of the digestion of foods is to change them Into soluble form. 21. The xjhite of an uncooked egg is soluble in water. 22. Hard-boiled eggs are more easily digested than soft- boiled eggs. 2 3. Carrots are a good soxirce of vitamin A. 2 l | . . Vitamin B is water-soluble. 25. Vitamin C Is easily destroyed by cooking in alkaline solutions. 26. Vitamin C is easily destroyed by exposure to'air. 27. Citrus fruits are a poor source of vitamin C. 28. Vitamin D is fat-soluble and is found in milk. 29. Vitamin G is found in vegetables. . 3 . 0 . The "waterless” .method of_ cooking vegetables prevents _ _ 172 loss of vitamins. 31. The cooking of vegetables destroys the cellulose which they contain. 32• The connective tissue of meat contains collagen. 33. Collagen is more soluble after heating. 3?i. Muscle tissue containing globulin is less soluble after being heated. 35. The rapid cooking of meat is a desirable method. 36. Meats contain large amounts of vitamins* 37. . Boasting is an example of the moist cooking of meat. 38. The best method of soft-boiling eggs is to boil them gently for three minutes. 39* Jellies are made with the use of propectin. l . j . 0 * Jellies are good examples of colloidal solutions. lj-1. Very ripe fruit produces the most pectin. ij- 2 . Baking powder and balling soda are the same compounds. i]-3* All leavening agents produce carbon dioxide. Yeast is one of the oldest leavening agents. I 4. 5 * A baking powder may be made by mixing the correct amounts of sodium bicarbonate, calcium acid phosphate, and sodium aluminum sulfate together. I { , 6 . Yeast converts sugar into alcohol and carbon dioxide. I 4. 7. Baking soda and sour milk make a good leavening agent. lj-8. Phosphate baking powders contain no alum. L j . 9 . Potassium acid tartrate is cream of tartar. £0. Double-acting baking powders contain two acid-forming compounds. EXERCISES FOR UNIT II In the statements which follow there are blanks to be; filled. On a separate sheet of paper write whatever is necessar?/ to fill the blanks correctly. 1. The process used in the preservation of food retards 2. The preservation of food makes possible more reasonably ________' foods otherwise they would be very _________ . 3. The preservation of food by __________ is based upon the - of x^ater. Ip. The amount of water which needs to be evaporated depends on the amount of __________ in the food. 5* A harmless food preservative is common ___________. 6. The most commonly used chemical preservative is 7. . ____________________ method of preserving does not pierce or destroy the cell walls of the food. 8. The principle involved in canning the foods is that of ___________ the through heat _ and then sealing the , thus preventing the entrance of any new germs from the ____ . 9. Home-canned vegetables may be a source of the disease known as EXERCISES FOR UNIT III In the statements which follow, there are blanks to be filled. On a separate sheet of paper write -whatever is necessary to fill the blanks correctly. 1. The modern kitchen should be supplied with ___________3 the kinds of cooking utensils. 2. Glass is a mixture of 3* Iron is undesirable as a material for cooking utensils because it ___________ easily. Ip. One should know how different cooking utensils ______ _____ foods. 5>* Aluminum is obtained from the __________ method. 6. __________ foods should not be cooked In aluminum utensils. 7. ___________ or roiled aluminum makes a very desirable cooking utensil. 8. Before iron is plated it must first have the ________ ____ removed by treating it with________ acid. 9. A thin coating of ___________ which accumulates on iron ‘ cooking utensils usually prevents much ___________. 10. Utensils used, in the home such as __________ and ______ _ are made by galvanizing Iron. 11. Galvanized iron is made by coating iron with __________ . 12. The enamel coating on enamelware has a composition similar to that of _______ . - 13. Copper is ___________ hydrogen in the activity series. l l | . . ___________ acids will oxidize copper in the presence of air. 1 5* ___________ glass can be made by mixing ________ _ oxides with the other ingredients used in ordinary glassmaking. EXERCISES FOR UNIT IV The statements which follow are incomplete* On a separate sheet of paper write whatever is necessary to complete each statement. 1. Earthenware bowls and pots were used in _________ times. 2. The making of dinnerware and the making of silverware are ___________ processes. 3* Silverware is desirable because it is possible to obtain a __________ polish on it. , I j . . Sterling silver contains __________ and ' ______ • 5. Silver is a metal which is sometimes found in the ___________ state. 6. German silver contains ___________, , and 7. Most silverware Is ___________ by the proces today. 8. Hollowware which has been plated is sometimes covered with lacquer, the reason for It not to ________. 9. The best quality of plated silverware is usually __________ plated. 10. Silverware should be stored in ___________ chests. 11. The tarnish which forms on silverware has the composi tion __________ . 12. Foodstuffs containing . ______ will easily tarnish silver. 13# Silver may be polished electrolytically by placing It In an ___________ pan containing a warm solution of __________ and ___________• llq. Silver polishes should contain no ___________. 15. The principal Ingredient in chinaware is ____________. 16. Feldspar, a complex silicate of ____________ is also used in making dishes. 17. Dinnerware Is fired in cylindrical cases called • 18. The temperature of the first firing of dinnerware Is about ___________, 19. The firing of dinnerware removes the water which is held physically and also that which Is held in ' _______ • combination. 20. A material, applied after the first firing, made of feldspar, flint, lead oxide, and water is called _____; _____. This material, when fired on dinnerware, produces a 21. There are usually _______ grades of dinnerware. Fine glassware for table use contains __________ and instead of sodium and calcium compounds* Glass can be etched by applying __________ acid. Another way of putting a design on glassware is by the ______ ___ process* EXERCISES FOR TJNIT V In each, of the following statements supply the missing word or words which will complete the statement. 1. An'Increasing use of clothing has accompanied the growth of ______ . 2* One important reason for studying the chemistry of clothing is to learn of the different ____ out of which clothing may he made. 3* One may identify different ' by means of and ' _________ tests. L l. Clothing protects the____________ of the body. 5. Clothing may be made of _______ or___________ fibers. 6. Wool fibers belong to a class of organic compounds known as ___________• 7. Silk differs from wool in that it does not contain the e 1 erne n t ___________. 8 . Wool is a warm fiber because of ___________ tfdead? f air. 9. Wool fibers are from one to __________ inches long. 1 0. The fact that woven wool is quite __________ causes wool clothing to hold its shape we IT. ~ 11. Raw silk fibers are composed of two protein substances, known as____________ and __________ . 12. The diet and food supply of a fur-bearing animal will determine the __________ of its fur. 1 3. Another factor affecting the __________ of the fur is the __________ of climate in which the animal lived. IJ4.. The two kinds of hairs on any fur-covered animal are known as____________ and __________ . 15. Linen is made up of practically pure ___________. 16. Linen comes from the ________plant. 17. Rayon is technically known as _________ cellulose. 18. A fiber x^jhich resembles wool fiber may be made from __________ , a product of milk. 19. The ability of a fabric to absorb water is known as its __________ power. 2Q. An animal, fat known as ___________ is obtained as a by-product in the processing of wool for weaving. 21. Wool and silk fibers are dissolved when put in EXERCISES FOR UNIT VI In each of the following statements supply the missing word o p words which will complete the statement. 1, ______ __ are used to dissolve grease, chex^ing gum, lipstick, and the like, 2, To use a _______ bleach, stretch stained material over bowl of steaming hot water, 3, ______ take up stains like blotters and do not leave rings. i f . * Stains that have dried or have been set by laundering may be __________ to r emove. 5. Valuable linens and clothes may be permanently spotted if stains are not removed __________ laundering. 6. The first step in removing blood from white cottons or linens Is In . 7. __________ is an important article for removing chewing gum. 8. Four _________ water from a height through the stain which is coffee or tea. 9. For egg or meat juice stains, do not use __________ water first; it may set the stain. 10. For fruit stains, do not use _ _ _ _ _ first; it may set the stain. 11. There is no satisfactory method to remove ________ from nonwashable fabrics. 12. To remove stains, moisten white cotton and expose it to ____________• 1 3. __________ _ is removed in the same manner as fruit stains. EXERCISES FOR UNIT VII On a separate sheet of paper write whatever Is necessary to complete each of the following statements correctly. 1. Add. two words to complete this word equation for the manufacture of soap: Fat plus ' becomes soap plus . 2. Hard water is usually due to the presence of _________^ and _________ sulfates and chlorides In* the water. 3. Two chemicals which, when added to water, help to soften it are ___________ and . I f . . Most of the coramerical bleaches now being sold are a chemical compound known a s ___________. 5>. A good chemical compound to add to water to be used for cleaning windows Is _____. 6. After the shut off valves in the home water system have been closed and the water drained, any remaining water may be kept from freezing by dissolving___________ in it. j 7* A grease trap which is clogged with grease may often be' opened with a hot solution of ___________ . 8. Two chemical substances which are good fumigants are and 9. Ants may usually be controlled in the home by using the chemical compound ____________. 10. Commercial fly sprays are usually a solution made by dissolving pyrethrum powder in __________ . 11. A garbage receptacle should be emptied at least once 12. Is added to rinse water in laundering to make white clothes whiter. EXERCISES FOR OTIT VIII The statements which follow are incomplete so com plete each statement correctly. 1* The __________ of colors used in paints was very limit ed before chemists became active in the field of colors. 2. Decorative materials are used in the home for the following reasons:____________ , ___________, and * 3. Painting preserves a surface because it prevents • Ix. Most paints consist of __________ , thinners, driers, and . __________ . 5# Gaseous __________ compounds cause white-lead paint to darken. 6. Titanium oxide pigment has great __________ power. 7. Barium __________ is considered an adulterant in paints. 8. Linseed oil oxidizes slowly when exposed to __________. 9. A common thinner for paints is ___________. 10. Red pigments usually contain __________ or___________ oxides. 11. Gloss in a paint may be obtained by using ___________. 12. Spirit varnish is made by dissolving __________ in 13* An enamel is a to ilhich has been added a . ♦ II4. . Lacquers are best applied with a ___________. 15. Linoleum is made from __________ oil, pigment, and ♦ 16. Washable wallpaper is wallpaper xlhich has been sprayed with a compound containing ___________ . 17* All dirt and __________ must be removed from the sur face before paint is applied. 18. Wallpaper is made by applying to paper a ground coat composed of ___________, a pigment, and a binder, such as ___________. 19. A wall-cleaner may be made by mixing ___________ with water. 20. In revarnishing a previously varnished surface, the kind of varnish should be used. University of Southern California Library UMI Number: EP47970 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Di&stttatior Pubi sh*ng UMI EP47970 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346

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Asset Metadata

Creator Lacouague, Grace Louise (author)

Core Title A course of study in household chemistry

School School of Education

Degree Master of Science

Degree Program Education

Degree Conferral Date 1955-06

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag education, sciences,OAI-PMH Harvest

Format masters theses (aat)

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c24-138194

Unique identifier UC11273574

Identifier EP47970.pdf (filename),usctheses-c24-138194 (legacy record id)

Legacy Identifier EP47970.pdf

Dmrecord 138194

Document Type Thesis

Format masters theses (aat)

Rights Lacouague, Grace Louise

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA