of Atmospherical Air, Ge. 157 
by the combustion of the former. The earth 
weighed nearly 53 grains, which agrees exactly with 
the weight of the chalk when the carbonic acid is 
deducted from it. i 
EXPERIMENT V. 
One hundred grains of the chalk, of which I 
made use in Experiment rv. and which were found 
to contain 47 per cent. carbonic acid, were calcin- 
ed in the fire of a smith’s forge. It lost all 
its carbonic acid, and the residuum weighed 53 
grains. . 
Now, if it were true, that carbonic acid, when in the 
state of gas, contains water to the amount of half 
its weight, the barytes in Experiment 1. would have 
weighed g grains more than it’did; and the lime 
in Experiments 11. 111. would have weighed 402 
grains more than it really did weigh; and the 
earth of Exp. rv. v. would have weighed 47 grains 
more; or, if the gas contained water in any other 
proportion, the earths must have weighed as much 
more as this water amounted to. But as the weight 
of the pure earths, and the carbonic acid gas toge- 
ther, corresponded with the original weight of the 
carbonats from which they came, it follows that 
nothing extraneous entered into the composition of 
that gas, except the caloric, which is necessary to 
its gaseous state. The inference also, which Dr. 
Priestley has drawn from his experiments on this 
subject, viz, that the greatest part of other gases -is 
