180 Experiments made at the Polytechnic School 
fpeétive quantities of carbon and oxygen which form the car- 
bonic acid. Mr. Tennant feems to have done the fame thing’ 
lately after the combuftion of the diamond by nitre. . But we 
fhould only have confirmed what was before known, or fup- 
pofed to be known. Our object was not only to obferve, with 
more attention, what took place during the aét of combuf- 
tion, but to afcertain,; as accurately as poffible, the nature 
and quantity of the product, and the reader will find that the 
Jabour undertaken on this fubjeCt has not been fruitlefs. 
The liquor was agitated in the globe to mix the white mat- 
ter which had been depofited. We drew out 4% meafures 
of the five we had introduced by making ufe of the fame in- 
verted bottle filled with mercury, and which we ratfed on the 
infide by means of an iron ftalk compofed of feveral pieces, 
which could be adjufted by ferews. (See fig, 6. Plate II.) 
We introduced into the balloon three new meatfures, each 
containing the fame quantity of diftilled water, which was 
fhaken in the infide to detach and colle€t what adhered to 
the fides. Thefe united liquors, being immediately filtered 
in an open filtre, left 192 centigrammes (36°142 grains) of 
garbonat of barytes dried in the heat of boiling water. 
It may be readily judged what was our aftontfhment when 
proceeding to examine the liquor, inftead of finding in it a 
flight excefs of uncombined barytes, we obferved that it 
changed neither the colour of turmeric nor that of logwood, 
and that, on the contrary, it acted on an infufion of turnfole 
as water charged with the carbonic acid. The prefence of 
this acid unequivocally manifefted itfelf, when we poured 
upon it a few drops more of barytes water, which immedi- 
ately rendered it turbid. It was neceflary to add even 4°65 
centimetres of this water to faturate and precipitate the re- 
maining acid gas. Being informed by this phenomenon that 
the produétion of the gas had been more confiderable than 
we expected, and that fome of it ftill remained mixed in the 
aériform fluid in the balloon, we took every meafure necef- 
fary to determine the quantity. This we. were luckily en- 
abled to do by the divifions which had been marked on the 
feales, the orifice of the globe having never been yet taken 
out of the mercury, 
When the barytes water was taken out, the apparent vo- 
lume 
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ae, 
