291 
Quantity of Carbon in carbonic Acid. 
manner. A quarter of an ounce of nitrate of potash was ren- 
dered somewhat alkaline by exposure to heat, in order that it 
might more readily absorb carbonic acid ; it was then put into 
a gold tube with grains of diamond, and being subjected to 
heat, the diamond, was converted into carbonic acid, by uniting 
with the oxygene contained in the nitric acid. The carbonic 
acid thus produced combined with the potash, and on pouring 
a solution of muriate of lime into a solution of this salt, he 
obtained a precipitate of carbonate of lime : this being decom- 
posed by muriatic acid, gave as much carbonic acid gas as oc- 
cupied the space of 10,1 ounces of water. The thermometer 
was at 55 0 Fahrenheit, the barometer 29,80. In a second 
experiment he procured a larger quantity, or equal to 10,3 
ounces of water. 
If we therefore consider an ounce of water as consisting of 
480 grains, and a cubic inch of water equal to 253 grains, and 
then make the proper corrections for temperature and pres- 
sure, one of his experiments will give about 27 per cent, the 
other about 27,80 for the carbon in carbonic acid, which is 
somewhat less than our estimate ; but the difference may easily 
be accounted for, from the different methods employed. 
The experiments of Guyton, as detailed in the Annales de 
Chimie, vol. XXXI, page 7 6, are liable to very strong objec- 
tions ; but at the same time the candid manner in which he 
has related every circumstance merits considerable praise. It 
is impossible, however, not to observe, that the quantity of 
gas before and after the experiment could not, from the con^- 
struction of his apparatus, be very rigorously ascertained. We 
object also to nitrous gas as a test for oxygene ; and. as it is 
acknowledged that the wooden support included in the oxy- 
gene gas took fire, the product of carbonic acid must have 
