JOURNAL OF AGEIdTDRAL RESEARCH 



DEPARTMENT OF AGRICULTURE 



Vol. V Washington, D. C, November 22, 191 5 No. 8 



AN IMPROVED RESPIRATION CALORIMETER FOR USE 

 IN EXPERIMENTS WITH MAN 



By C. F. Langworthy, Chief, and R. D. Milner, Assistant Chief, 

 Office of Home Economics, States Relations Service 



INTRODUCTION 



The nutrition of the human body consists mainly in the transforma- 

 tion of food into body material and the ultimate transformation of the 

 energy potential in both food and body material into such forms of 

 energy as heat and muscular work. The transformations of both food 

 and body material occur largely in accordance with the needs of the 

 body for energy. To understand the laws governing the nutrition of the 

 body, knowledge regarding these transformations of matter and energy 

 is essential. 



To obtain such knowledge it is necessary to have some means of 

 determining the intake and output of both matter and energy by the 

 body. This involves the use of some form of apparatus that will give 

 an accurate measurement of the gaseous exchange and the energy pro- 

 duction of the body. Such an apparatus is the so-called respiration 

 calorimeter employed in connection with the nutrition investigations of 

 the Department of Agriculture. 



The first apparatus of this kind constructed in this country was de- 

 veloped in connection with these investigations. Work on this device 

 was begun in 1892 by Prof. W. O. Atwater at Wesleyan University, 

 Middletown, Conn. When the Department of Agriculture undertook an 

 inquiry into the food and nutrition of man in 1894 as a logical outgrowth 

 of the earlier work of Prof. Atwater for the Smithsonian Institution and 

 the United States Department of Labor, the need of some means of 

 determining the income and outgo of matter and energy in the body was 

 recognized, and the general plan of work to be undertaken as part of the 

 inquiry was made to include experiments with the respiration calorimeter 

 which had been devised for measuring factors of outgo. 



For use in the study of the output of matter by the body, the device 

 was similar in principle to the respiration apparatus of Pettenkofer(i6),* 



' Reference is made by number to "Literature cited." p. 346-347. 



Journal of Agricultural Research, Vol. V, No. 8 



Dept. of Agriculture, Washington, D. C. Nov. 22, 1915 



as B-s 



(299) 



