JOURNAL OF AGWCDLTDRAL RESEARCH 
DEPARTMENT OF AGRICULTURE 
Vol. V Washington, D. C., November 22, 1915 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), 1 
1 Reference is made by number to “Literature cited,” p. 346-347. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
as 
Vol. V, No. 8 
Nov. 22, 1915 
B—s 
(299) 
