294 d)r. Priestley’s Experiments and QbfervaUom 
Notwith (binding the above-mentioned variations, the lofs of 
weight in the charcoal was always much exceeded by the weight 
of the water expended, which was generally more than double 
of the charcoal; and this water was intimately combined with 
the air; for when I received a portion of it in mercury, no 
water was ever depofited from it. 
The experiment which, upon the whole, gave me the mod: 
fatisfaclion, and the particulars of which I fhall therefore re- 
cite, was the following. Expending 94 grains of perfect 
charcoal (by which I mean charcoal made with a very ftrong 
heat, fo as to expel all fixed air from it) and 240 grains of 
water, I procured 840 ounce meafures of air, one-fifth of 
which was fixed air, and of the inflammable part nearly one- 
third more appeared to be fixed air by decompofition. 
Receiving this kind of air in a variety of experiments, but 
not in the preceding ones in particular (for then I could not 
have afcertained the quantity of it) confiding of fixed and in- 
flammable air together, I found fome variations in its fpecific 
gravity, owing, I imagine, to the different proportions of 
fixed air contained in it ; but upon the whole, I think, that the 
proportion of 14 grains to 40 ounce meafures is pretty near the 
truth, when the proportion of fixed air is about one-fifth of the 
whole. With refpe'ft to the weight of the inflammable air after 
the fixed air was feparated from it, I found no great difference, 
and think it may be eflimated at 8 grains to 30 ounce meafures. 
Upon thefe principles, the whole weight of the 840 ounce 
meafures of air will be - 294 grains 
that of the charcoal will be 94 
that of the water - 240 
334 which, confidering the na- 
7 ture 
