NEW FORM OF BOMB CALORIMETER. ' 135 
Dene W FORM OF BOMB CALORIMETER AND DETER- 
MINATIONS OF HEATS OF COMBUSTION. 
BY WO, ATWATER AND CHAS, DD. WOODS, 
———# ¢ o—__—__ 
THE BOMB CALORIMETER. 
During the past five years the reports and bulletins of this 
Station have contained frequent reference to the fuel values of 
food materials and the need of more definite information regard- 
ing not only the potential energy of food, but also the more 
general subject of the transformation of energy in the living 
organism.* 
The later development of experimental science has given us 
clearer ideas not only of the chemical, but also of the physical 
changes that take place in the animal and in the plant. Tothese 
processes it has become customary to apply the term metabolism. 
The processes of metabolism in the body are of two definite but 
closely allied kinds—the metabolism of matter and the metabol- 
ism of energy. It is commonly assumed that these two processes 
conform, the one to the law of the conservation of matter and 
the other to that of the conservation of energy. Exactly this 
form of statement is not usual, but the principles thus enunciated 
have been more or less definitely assumed by writers and experi- 
menters during the last twenty years or more. ‘The bringing of 
the metabolic processes into line with these two fundamental laws 
helps greatly toward simplifying the whole subject, clearing up 
details that have been obscure, and placing the doctrine of nutri- 
tion upon a rational and simple basis. In the light of these laws 
many of the results of experimenting are more easily interpreted, 
imperfections in plan and errors in execution of past experiment- 
ing are brought out, and the ways in which the unsolved problems 
before us may best be studied are laid open. Experimenter, 
teacher, and student alike are helped by such a coérdination 
of principles. At the same time the theory of nutrition thus 
becomes plainer to the practical man. He can understand it 

* See, especially, Report for 1890, p. 174. 
