6 NEW HAMPSHIRE EXPERIMENT STATION [Bull. 242 



ture of proteins, fats and carbohydrates, we could assume an average 

 value of 4.825 calories for each liter of oxygen required in the com- 

 bustion of a mixed food and compute the energy value of the food 

 from the measured oxygen with an error of hardly plus or minus 3 

 per cent. Measurement of the carbon-dioxde production has been 

 relatively simple, but until recently measurement of the volume of 

 oxygen consumed has been accomplished only under the most difficult 

 conditions. The progress in the development of respiration apparatus 

 has, however, been such that today it is actually less difficult to 

 measure the oxygen absorbed during a combustion than to measure 

 the carbon dioxide produced. The simpler technique for de- 

 termination of the heat of combustion of foods, therefore, requires at 

 the present day not the use of the complicated bomb calorimeter, not 

 the complex calculations from chemical analyses, but the direct 

 measurement of, the volume of oxygen consumed per gram of food 

 substance burned, and the multiplication of this volume by the 

 known caloric value of a liter of oxygen, according to the character 

 of the substance burned. 



PLAN OF RESEARCH 



Based upon this simpler technique for the determination of the 

 energy values of foods, a cooperative research i was undertaken by 

 the Nutrition Laboratory of the Carnegie Institution of Washington, 

 in Boston, Massachusetts, and by the New Hampshire Agricultural 

 Experiment Station at Durham, New Hampshire. The object of this 

 research has been to secure data regarding the energy and the pro- 

 tein content (1) of several individual foods, such as breads, pastry, 

 soups, sandwiches, salads, desserts, ice creams, and candies; (2) of 

 the total meal, — breakfast, dinner and supper; and (3) of the total 

 food consumed per day by an individual. 



The samples of food analyzed were for the most part secured 

 either in Boston or in Durham. Three types of eating places are rep- 

 resented: — (1) the commercial restaurant where it is the custom to 

 serve supposedly "standardized" meals for a fixed price, particularly 

 at noon; (2) the college cafeteria where the meals are combinations of 

 various portions or servings of food according to the choice of the 

 individual; and (3) the drugstore where sandwiches and ice-cream 

 mixtures may be obtained. At the college cafeteria no attempt was 

 made to secure necessarily the most economical food combinations, 

 but the basis of selection was the choice of the operator or the dupli- 

 cation of the choice of the individual immediately preceding the 

 operator in line. 



(1) During the first year of this research Miss Mary E. A. Pillsbury 

 cooperated with us in making these food analyses. We wish to express here 

 our deep appreciation of her able assistance. 



