4 A RESPIRATION CALORIMETER. 



was placed in a closed chamber inside a larger room of constant tempera- 

 ture. The rise in temperature of the inner chamber was noted and the 

 heat emission thereby calculated. Similar types have been those of 

 d'Arsonval, 1 Him, 2 and Vogel. s 



The newer forms are of two types : First, those in which the heat 

 delivered from the body is lost through the walls by radiation and the 

 calorimeter calibrated by determining the radiation constant ; and, 

 second , those in which the heat developed is brought away by a cooling 

 current of water flowing through the calorimeter chamber, the radiation 

 constant being eliminated as far as possible. One of the most recent 

 forms of the first type of apparatus is the ' ' emission ' ' calorimeter of 

 Chauveau ; 4 the second type is that employed originally by Atwater and 

 Rosa, 5 and in its more developed form is to be described beyond. 



THE RESPIRATION CALORIMETER. 



As has been stated, the more satisfactory experiments are those in 

 which the transformations of both matter and energy are studied. 

 For such experiments it is essential that the apparatus used be so con- 

 structed as to afford opportunity for" measuring at the same time both 

 the respiratory products and the energy given off from the body. 

 Among the various forms of apparatus referred to in the preceding 

 paragraphs some were so constructed, and such is especially the case 

 with the apparatus here to be described. To indicate its twofold func- 

 tion as a respiration apparatus and as a calorimeter, it is designated a 

 " respiration calorimeter." As will be explained in detail, the respi- 

 ration apparatus is of the ' ' closed-circuit ' ' type of Regnault and 

 Reiset ; the calorimeter is a constant-temperature, continuous-flow 

 water calorimeter. 



In addition to the measurements of respiratory products and energy 

 made directly by the apparatus, the experiments include, in determi- 

 nations of matter, the analyses of the air in the apparatus and measure- 

 ments of the amounts of oxygen introduced, and the weighing and 

 analyzing of the food, drink, and solid and liquid excreta ; and in deter- 

 minations of energy the measurement of the potential energy, i. e., 

 heats of oxidation, of the solid ingredients of food, drink, and excreta. 

 All these data constitute the factors of total income and outgo of both 

 matter and energy. 



1 Soc. de Biol. (1894), 27, i. 



*Recherches sur 1' Equivalent mecanique de la chaleur (1858). 



3 Arch. d. Ver. f. wiss. Heilk. (1864), p. 422. 



4 Comptes reudus (1899), 129, p. 249. 



5 U. S. Dept. of Agr., Office of Experiment Stations Bull. 63. 



