277 
Quantity of Carbon in carbonic Acid. 
Correction for Pressure. 
30:30,2 : : 51,69 : 52,03. 
The volume, therefore, at mean pressure and temperature, 
would have beeen 52,03 cubic inches. 
We now lighted a fire in the small black lead furnace underthe 
platina tube, and as soon as it became red hot, opened the cocks 
and passed the gas from No. 1 to No. 2, when the charcoal enter- 
ed into vivid combustion, and heated the platina tube white hot. 
The operation was repeated many times during 6 or 7 minutes, 
by pressing alternately upon the glasses of the gasometers. Not 
the least flash of light was observable in the glass connecting 
tubes GG, nor the smallest appearance of moisture. The fur- 
nace being removed, the tube was now cooled by the application 
of wet cloths ; and when all was reduced to the temperature of 
the room, we pressed upon the glass of gasometer No. 2, so as 
to force all the gas into No. 1. The cock below being closed, 
we tried the tubes, &c. and found them perfectly air-tight. We 
next unscrewed the tube and took out the platina tray ; but it 
only contained a light white ash, somewhat resembling the 
shape of the pieces of charcoal, and weighing only ,02 of a 
grain. On observing the register of No. 1, it indicated ex- 
actly the quantity of gas that we began with, so that although 
3,98 grains of charcoal had been dissolved, the volume of gas 
was unaltered by it ; a circumstance which had been remarked 
before by Lavoisier. The small receiver R was now nearly 
full of mercury ; the communication with the gasometer being 
opened, the large glass receiver was gently pressed upon, 
until several cubic inches were forced through the receiver R, 
and tube K, in order to clear the latter of common air. This 
being done, on trying our gas with the eudiometer and lime 
MDCCCVII. O O 
