446 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



The Storrs Experiment Station had already done considerable work 

 along similar lines before the institution of the national inquiry into 

 the food and nutrition of man, and has continued such work from the 

 beginning of this inquiry to the present time. Since 1895 the State 

 has annually appropriated $1,800 to the station, the major portion of 

 which has been available for the nutrition investigations. 



IMPROVEMENT OF APPARATUS — BOMB AND RESPIRATION CALORIMETERS. 



One important function of food is to furnish energy to the body. 

 For a thorough study of the laws of nutrition, therefore, and of the 

 uses and nutritive values of food, there must be a means of determin- 

 ing the amounts of potential energy in the food consumed and in the 

 products formed from the food by the body. Since different forms of 

 energy may be transformed into heat, the energy of a substance may 

 be expressed in terms of heat, and therefore the potential energy of a 

 substance may be measured b} 7 the heat developed when the substance 

 is burned in oxygen. In the investigations conducted under the aus- 

 pices of the United States Department of Agriculture a very satisfac- 

 tory method is emplo} r ed whereby the amount of heat thus developed 

 by food materials is determined. The result obtained in this way is 

 called the " heat of combustion" of the material burned. The appa- 

 ratus used for this purpose is called a calorimeter. Various forms of 

 calorimeter have been devised. That form now in use in connection 

 with the nutrition investigations of this Office is called a bomb calorim- 

 eter. The early work done by the Connecticut Storrs Station along 

 this line was with a Stohmann calorimeter, a modification of an earlier 

 form devised by Thompson. This apparatus proved unsatisfactory, 

 and the attempt was made to secure a better one. The bomb calorim- 

 eter devised by Berthelot was superior, but was very costly because 

 of the large amount of platinum used in its construction. With the 

 aid of Professor Hempel, of Dresden, Professor Atwater and his 

 associates succeeded in modifying the Berthelot apparatus, especially 

 with regard to the amount of platinum used, so that a very accurate 

 and satisfactory calorimeter has been obtained at a much lower cost. 

 By the use of this apparatus the heats of combustion of a large number 

 of different food materials have been determined. 



Studies of some of the more fundamental laws of animal nutrition 

 have been carried on for the purpose of determining what uses the 

 body makes of its food under different conditions. Special inquiries 

 of this nature were begun by Professor Atwater in 1892, by means of 

 an apparatus known as a respiration calorimeter, so arranged that a 

 man may spend a number of days in comparative comfort within it, 

 and so manipulated that the metabolism of both matter and energy in 

 his body may be determined. In devising and perfecting the apparatus 

 and in carrying out the investigations with relation to the measure- 





