682 
DE. E. SMITH OX THE CHEMICAL 
inspired, or to what extent the ah was resphed more than once; and it was not easy to 
nrove how much carbonic acid remained in the box. .^47 
3rd The method of Andeal and Gavaeeet^, by which a mask of the capacity of am 
ordinary expiration was placed over the whole face, and a continnons current of an 
made to pass through it into an analytical apparatus without respnatoiy e oi ^ ^ 
As the motor power was a vacuum produced in the receiver of the expned air the 
duration of each inquii-y was limited to about half an hour ; and as all the an admitted 
to the mask and the receiver did not enter the lungs, it was not possible to deteimme 
the volume of air insphed. n- j 
Hence it was necessary, in order to pursue any serial and long-continued inquiry, 
devise a method which had not been adopted by previous observers. . ^ , 
The apparatus which I prepared for the purpose, after a long senes of expenments, to 
already been presented to the Koyal Society, and it differs from any heretofore employed, 
inasmuch as during the act of expiration, and for any length of time it abstracts the 
whole carbonic acid exhaled by the lungs. With it was conjomed a smaU diy gas-meter, 
to measure the volume of the inspired air, as described in my former paper. The appara- 
tus and method may be thus briefly described. 
* Aimales de CHmie, voL viii. p. 129. 
