A RESPIRATION CALORIMETER, WITH APPLIANCES FOR 

 THE DIRECT DETERMINATION OE OXYGEN. 



BY W. O. ATWATER AND F. G. BENEDICT. 



INTRODUCTION. 



For a proper understanding of the metabolism or transformations of 

 matter and energy in the body, a knowledge of both total income and 

 total outgo is indispensable. Physiologists and physicians have long 

 been accustomed to depend very largely upon data from the analysis of 

 urine for information regarding the metabolism of matter, especially 

 of proteid, in the body. In many cases, aside from gross or approxi- 

 mate estimates of the quantities of food ingested, they made no attempt 

 to determine the income, and the outgo of material in the feces was, as 

 a rule, entirely neglected. In a study of the metabolism of proteid in 

 the body the analyses of the urine have a very great significance, which 

 in the light of recent researches, such as those of Folin 1 and Burian,'is 

 becoming even more intelligently comprehended. But it has been long 

 understood that many other transformations of matter besides those 

 in which the element nitrogen is involved occur in the body, for the 

 proper study of which a knowledge of the income of carbon, hydrogen, 

 oxygen, water, and mineral matters, in addition to that of nitrogen, is 

 necessary ; and, since the disintegration of the proteids as well as of 

 the fats and carbohydrates of the body is accompanied by an absorp- 

 tion of oxygen from the air and an elimination of carbon dioxide and 

 water, our knowledge of the outgo must include not only the quantity 

 of nitrogen in the urine, but also the amounts of carbon dioxide and 

 water excreted by the lungs and skin, and of the carbon, hydrogen, 

 oxygen, and mineral matters of both urine and feces. 



Furthermore, for many purposes the measurement of intake and 

 output of matter is not wholly sufficient, but must be supplemented 

 by determinations of the transformations of energy, because one of the 

 chief functions of food is to supply the body with energy. Moreover, 

 the study of the transformations of matter is rendered more complete 

 and intelligible by a knowledge of the transformations of energy. 



1 Amer. Journ. Physiol. (1905), 13, pp. 45-115. 

 'Zeits. f. physiol. Chem. (1905), 43, p. 532. 



IB 



