94 STORRS AGRICULTURAL EXPERIMENT STATION. 
The accurate determination of water has been found less 
easy. ‘The difficulty appears to rest not so much in the deter- 
mination of moisture in the current of air asin the getting of 
all the moisture into the current. ‘The water to be determined 
is the whole given off from the body of the subject in the res- 
piration chamber, less the amount removed in feces and urine. 
Practically this means the water exhaled through the lungs 
and skin. For our present purpose it may be designated as 
water of exhalation, and taken as including the water of res- 
piration from the lungs and that of perspiration from the skin. 
While the efforts to obtain all the exhalation water in the 
_ current of air coming out of the respiration chamber were 
. not entirely successful, not a little labor was devoted to the 
study of ways to determine accurately the amounts of both 
carbon dioxide and water in the currents. "The success here 
was on the whole decidedly gratifying. Various reagents for 
absorption and methods of manipulation were tried. We 
finally settled upon the plan of cooling both the incoming 
and outgoing currents of air to remove the larger part of the 
water and passing sainples over sulphuric acid to determine 
the rest. For determining the carbon dioxide we have had 
better success with soda lime as an absorbent than with either 
potassium hydroxide, solid or in solution, or barium hydrox- 
ide solution by the well known Pettenkofer method. 
Determination of water.—As explained above the most of 
the water of both the incoming and outgoing currents of air 
was removed in passing through the freezers, of which there 
was one series of two freezers for each current. ‘The water 
condensed from the incoming current was not weighed, that 
condensed from the outgoing current was weighed. The 
amount remaining in the air after it had left the freezers was 
determined by passing a sample over sulphuric acid in U tubes. 
Absorption of carbon dioxide.—As above stated, soda lime has 
proven the most satisfactory reagent, but it must, however, 
have the proper proportions of soda lime and water to fit it for 
the purpose. ‘The presence of a certain amount of moisture in 
the soda lime is essential to the complete absorption of the CO,. 
The tests of the accuracy of the methods thus described for 
determining the H,O and CO, in the air from the respiration 

