16 STORRS AGRICULTURAL EXPERIMENT STATION. 
STUDIES. OF DIETARIES. 
These have been of the same general character as those 
described in previous Reports of the Station and are in continu- 
ation of an investigation which is being made by codperation 
with the U. S. Department of Labor. 
INVESTIGATIONS OF THE BOMB CALORIMETER. 
The study of food and nutrition has brought us to a point 
where it is essential to learn the fuel value of food materials, 
or in other words, the amounts of potential energy which they 
contain and which may be changed to heat or the muscular 
power or other form of energy in the body. ‘The apparatus for 
this purpose is called the calorimeter. Investigations with a 
form of calorimeter were described in the Report for 1890. A - 
form which has proven more satisfactory is the so-called bomb 
calorimeter. Hitherto the only satisfactory bomb calorimeter 
has been that of Berthelot, but its great cost, $1,000 or more, 
which is due to the large quantity of platinum required for its 
construction, has prevented its general use. With the aid of 
Prof. Hempel, of Dresden, I have succeeded in obtaining a bomb 
calorimeter which costs not more than $100 or $200, and proves 
quite satisfactory. ‘The effort is now being made to devise one 
which shall be less expensive. 
RESPIRATION CALORIMETER. 
Research upon nutrition has brought us to the point where the 
study of the application of the laws of the conservation of matter 
and of energy in the living organism are essential. That isto say, 
we must be able to determine the balance of income and outgo of 
the body, and this balance must be expressed both in terms of 
matter and of energy. For this purpose a respiration calorimeter 
is being devised. ‘This is an apparatus in which an animal or a 
man may be placed for a number of hours or days and the 
amounts and composition of the food and drink and inhaled air; 
the amounts and composition of the excreta, solid, liquid and 
gaseous; the potential energy of the materials taken into the body 
and given off from it; the quantity of heat radiated from the 
body; and the mechanical equivalent of the muscular work done 
are all to be measured. ‘The experimenting is complicated, costly 
and time-consuming. The results already obtained are, however, 
very encouraging in their promise of future success. 
W. O. ATWATER. 

