1. Heat a little oil or other fat in a test tube until it turns brown and dense brown fumes are given off. Note the irritating effect of these fumes. Continue heating until no further change takes place. 2. Heat a little glycerine until similar dense brown fumes are given off. Note. Only exceedingly small portions of above should be used in the last experiments, to avoid excess of the disagreeable fumes. QUESTIONS 127 TOPICS FOR STUDY OR DISCUSSION 1. The physical structure of fatty or adipose tissue. 2. The chemical composition of fat. The principal fatty acids and how their predominance in the common fatty foods affects the solidity, the melting point, etc., of these foods. 3. The value of fat as food, its digestion and assimila- tion. The amount required in health. Its use in disease. 4. Fat as a protein sparer; how it compares with the carbohydrates, with gelatine, as a proteid sparer. Nations and races that make abundant use of fat in the diet. 5. The difference between the fats and the hydrocar- bons. The difference between the fixed and the volatile oils. 6. Industries which deal with fats; the lard-making and fat-rendering industry; the soap manufactories; the manufacture of olive oil, of cottonseed oil, etc. 7. Food laws which relate to various fats. 8. The value of salads in the diet. The elements in salads that are nutritious, or tissue building ; the elements that are wholesome, appetizing, purifying to the system by the action of vegetable acids or salts, etc. 9. National customs with regard to the use of salads. 10. Conditions under which aconitic and acrylic acids are formed during cooking processes. Note. Much that is new, and that has an important bearing on the fats, is now being brought out by organic chemistry. Advanced students will be interested to study the later theories of em ulsifi cation, colloidal solution, hydrolysis, and saponification if they are qualified by previous training to pursue the subject. Very important problems will be found to be involved in trying to understand what kind of change is brought about in the mixing of even such a simple thing as a French dressing — not to speak of a mayonnaise. QUESTIONS 1. Discuss the costliness of some of the fatty foods. Name some of the less expensive fats, and suggest methods of making them palatable. 2. What foods are especially deficient in fats? 128 PRINCIPLES OF FOOD PREPARATION 3. Name some foods rich in both fat and protein. 4. Name some foods rich in fat and carbohydrate. 5. In what diseases is fat thought to be especially bene- ficial? In what cases should it be sparingly used? 6. When, broadly speaking, may fat be preferable to carbohydrate, and when may carbohydrate be preferable to fat, as a source of energy? Consider, in this answer, various occupations, factory workers, sempstresses, farm- ers, lumbermen, tailors, etc. 7. Which fatty foods are rich in stearin? which in olein? What is peculiar about butter as a fatty food? What happens when butter or other fats become rancid? 8. Why, in making a white sauce, should you be very careful merely to soften the butter, and not to overcook it, preparatory to blending with it the other ingredients? 9. Discuss oleomargarine vs. butter for table use; for use in cooking.

AI-modernized reading of the original text

1. Heat a little oil or other fat in a test tube until it turns brown and dense brown fumes are given off. Note the irritating effect of these fumes. Continue heating until no further change takes place. 2. Heat a little glycerine until similar dense brown fumes are given off. Note. Only exceedingly small portions of above should be used in the last experiments, to avoid excess of the disagreeable fumes. 1. The physical structure of fatty or adipose tissue. 2. The chemical composition of fat. The principal fatty acids and how their predominance in the common fatty foods affects the solidity, the melting point, etc., of these foods. 3. The value of fat as food, its digestion and assimilation. The amount required in health. Its use in disease. 4. Fat as a protein sparer; how it compares with the carbohydrates, with gelatine, as a proteid sparer. Nations and races that make abundant use of fat in the diet. 5. The difference between the fats and the hydrocarbons. The difference between the fixed and the volatile oils. 6. Industries which deal with fats; the lard-making and fat-rendering industry; the soap manufactories; the manufacture of olive oil, of cottonseed oil, etc. 7. Food laws which relate to various fats. 8. The value of salads in the diet. The elements in salads that are nutritious, or tissue building ; the elements that are wholesome, appetizing, purifying to the system by the action of vegetable acids or salts, etc. 9. National customs with regard to the use of salads. 10. Conditions under which aconitic and acrylic acids are formed during cooking processes. Note. Much that is new, and that has an important bearing on the fats, is now being brought out by organic chemistry. Advanced students will be interested to study the later theories of emulsification, colloidal solution, hydrolysis, and saponification if they are qualified by previous training to pursue the subject. Very important problems will be found to be involved in trying to understand what kind of change is brought about in the mixing of even such a simple thing as a French dressing — not to speak of a mayonnaise. 1. Discuss the costliness of some of the fatty foods. Name some of the less expensive fats, and suggest methods of making them palatable. 2. What foods are especially deficient in fats? 3. Name some foods rich in both fat and protein. 4. Name some foods rich in fat and carbohydrate. 5. In what diseases is fat thought to be especially beneficial? In what cases should it be sparingly used? 6. When, broadly speaking, may fat be preferable to carbohydrate, and when may carbohydrate be preferable to fat, as a source of energy? Consider, in this answer, various occupations, factory workers, sempstresses, farmers, lumbermen, tailors, etc. 7. Which fatty foods are rich in stearin? which in olein? What is peculiar about butter as a fatty food? What happens when butter or other fats become rancid? 8. Why, in making a white sauce, should you be very careful merely to soften the butter, and not to overcook it, preparatory to blending with it the other ingredients? 9. Discuss oleomargarine vs. butter for table use; for use in cooking.

Principles of food preparation