Quantity of Carbon in carbonic Acid. %6g 
cf the tube are mounted with female screws of brass, to one 
of which the acommodating screw socket AS was joined. 
T is a double section of the platina tray which contained 
the substances to be heated. During their combustion, it was 
made to slide easily within the platina tube P. The accommo- 
dating socket and platina tray, are drawn considerably larger 
in proportion than the instrument. 
By means of the triple socket and the cocks, the gas was 
made to pass freely over the substances in combustion, from 
one gasometer to the other ; and by shutting off the communi- 
cation with the platina tube, while that with the small receiver 
was open, any portion of gas in the gasometer, fig. 1. might 
be transferred into eudiometers or measures standing in the 
mercury bath M, for examination. 
In order to discover whether the several sockets were air- 
tight, after the apparatus was put together, the communication 
with the gasometer, fig. 1, was closed, and the other communi- 
cations opened; the receiver of the gasometer, fig. 2, being 
raised, drew up a column of mercury in the small receiver R, 
equal to two inches : the communication with the gasometer 
was then closed, and the column was supported without alter- 
ation. This was always tried previous to, and after every ex- 
periment. As the joints would bear this degree of exhaustion, 
we were confident they would resist a much greater pressure 
than we had any occasion to employ. The glass tubes GG, 
which connected the platina tube with the gasometers, enabled 
us to observe any flash arising from the combustion of hy- 
drogene which might be contained in the substances subjected 
to experiment. In order to avoid prolixity, we shall generally 
state the method which was invariably followed. 
Nn 
MDCCCVII. 
