
CONSERVATION OF ENERGY IN LIVING ORGANISM. 105 
perhaps unnecessary for the study of a question about which 
there was really little doubt, and some persons may even doubt 
whether the experiments which have been reported suffice for 
the final and absolute demonstration that the law of the con- 
servation of energy always obtains in the body; but it will be 
worth while to consider here what the experiments are and 
what they do show. | | 
The experiments here considered, which were much more 
elaborate than those referred to above, were carried on within 
the past four years by the writer and associates at Wesleyan 
University, in cooperation with the Storrs Experiment Station 
and the U. S. Department of Agriculture. In these the quan- 
tities and potential energy of the materials burned in the body 
have been measured, as has also the energy given off from the 
body in the forms of both heat and muscular work. ‘The 
agreement between the potential energy (heat of combustion ) 
of the material oxidized in the body and the kinetic energy 
given off from the body in the forms of heat and,(the heat 
equivalent of ) external muscular work was so close as to imply 
that practically all the energy of the material burned in the 
body was transformed into measurable kinetic energy in ac- 
cordance with the law of the conservation of energy. 
The experiments were made with a respiration calorimeter 
which was especially devised for research of this kind. The 
apparatus serves to measure the materials received and given 
off from the body, including the products of respiration, and is 
thus a ‘‘ respiration apparatus;’’ it also serves to measure the 
heat given off by the body and-hence is a form of calorimeter. 
To indicate this two-fold purpose it is called a ‘“‘ respiration 
calorimeter.’’ As accounts of this apparatus and of methods 
eps 
and results of experimenting with it have been published in 
detail elsewhere* a brief description will suffice here. 

*In the following bulletins of the Office of Experiment Stations of the United 
States Department of Agriculture: No. 44, Report of Preliminary Investigations on 
the Metabolism of Nitrogen and Carbon in the Human Organism with a Respiration 
Calorimeter of Special Construction, by W. O. Atwater, Ph. D., C.D. Woods, Base 
and F. G. Benedict, Ph. D.; No. 63, Description of a New Respiration Calorimeter and 
Experiments on the Conservation of Energy in the Human Body, by W. O. Atwater, 
mt), and E. B. Rosa, Ph. D., pp. 94; No. 69, Experiments on the Metabolism of 
Matter and Energy in the Human Body, by W. O. Atwater, Ph. D., and F. G. Bene- 
dict, Ph. D.. with the coéperation of A. W. Smith, M. S., and A. P. Bryant, M.S., pp. 
‘112; No. 109, Experiments on the Metabolism of Matter and Knergy in the Human 
Body, 1898-1900, by W. O. Atwater, Ph. D., and F. G. Benedict, Ph. D., with the coép- 
eration of A. P. Bryant, M.S., A. W. Smith, M.S..and J. F. Snell); Ph. D, “See also 
/ articles in preceding reports of this Station. 
‘ 
8 
ae 
' 
4 
Pye 
ye 
