May, 1929] FOODS IN A COLLEGE COMMUNITY 13 



_ 149 X 20.80 X 1.0112 x 0.886 



-= 1089 c. c. 0. 



2.55 



Another analysis gave a value of 1097 c. c. of oxygen, the average 

 reduced volume therefore being 1093 c. c. 



This reduced volume of oxygen consumed per gram of air-dry 

 sandwich burned must be corrected for the amount of nitrogen liber- 

 ated per gram of air-dry sandwich during the combustion. The 

 Kjeldahl analyses indicated that the air-dry sandwich contained on 

 the average 2.52 per cent of nitrogen. Since one milligram of nitro- 

 gen occupies 0.8 c. c. under standard conditions of temperature and 

 pressure, the total volume of nitrogen liberated in the combustion of 

 one gram of air-dry chicken sandwich was 20 c. c. Therefore, the 

 average reduced volume of oxygen per gram of air-dry substance, 

 1093 c. c, should be increased by 20 c. c, and the total is thus 1113 

 c. c. or 1.113 liters. Multiplication of this value by 4.825,1 the caloric 

 value of a liter of oxygen when mixed foods are burned, gives 5.4 

 calories per gram of air-dry matter. Since the air-dry weight of 

 the total sandwich was 37 grams, the total energy content of the sand- 

 wich is 200 calories and the total protein content (assuming one 

 gram of nitrogen equals 6.25 grams of protein) is 5.8 grams. 



DISCUSSION OF RESULTS 



Tabulation of data. The actual determinations made were the 

 fresh weight, the air-dry weight, the nitrogen content, and the oxy- 

 gen required during the combustion of the air-dry food. The results 

 of these determinations are summarized in the following tables, includ- 

 ing calculations of the total energy and the total protein in the food 

 per serving or per unit as sold, and the calories per gram of air-dry 

 matter. In addition, in order to study the economic value of the 

 different foods, the cost of each food unit and the calories and protein 

 which may be purchased for 10 cents are also given in most instances. 

 The prices listed are those current during 1927 and 1928. Numbers 

 were assigned to the food samples in the chronological order in which 

 they were analyzed. Thus, the time intervening between the analysis 

 of sample No. 1 and the last sample. No. 477, is two years; and the 

 time elapsing between repeated analyses of the same kind of food is, 

 therefore, roughly indicated by the sample numbers. 



BREADS AND MUFFINS 



Since innumerable analyses of the various kinds of bread have 

 already been made, our study of this type of food was limited to 

 analyses of individual slices or single rolls or muffins, with the object 



(1) In the case of samples which were decidedly greasy the factor 4.7 

 has been used. 



