decompounding fixed Air. 299 
grains ; for 32 grains of charcoal combined with 72 of respirable 
air compose 104 grains of carbonic acid, or 70 ounce measures ; 
to which must be added the 25 ounce measures of undecom- 
pounded carbonic acid separated. Then the quantity of this 
elastic fluid, calculated to be decompounded, and remaining 
united in about 400 grains of mild fossil alkali, is 95 ounce 
measures, and the quantity of it actually found to exist in an 
equal weight of alkali, was about 112 ounce measures: there- 
fore the quantity of charcoal produced does not differ very con- 
siderably from that calculated to be contained in the carbonic 
acid decompounded. But future experiments must deter- 
mine whether there is a like coincidence with respect to the 
other supposed constituent of carbonic acid, namely, respirable 
air. 
I deem it unnecessary to relate a number of experiments 
which I have made, the result of which was similar to the 
preceding one; but it may be proper to mention, that in every 
instance, the proportions of phosphoric acid and charcoal 
were inversely as the quantity of carbonic acid remaining in 
the alkali ; and that the quantities of these two products 
diminished as the quantity abovementioned of phosphorus 
was diminished ; accordingly, the alkali most exposed to the 
phosphorus contained the greatest proportion of charcoal. 
I made this experiment several times with alkali, which con- 
tained a good deal of water, and then I obtained a large quan- 
tity of air, which smelt of phosphorus, but did not explode on 
contact with atmospheric air ; it contained no carbonic acid, 
nor phlogisticated air, excepting a few ounce measures in the 
first jar that came over, but it exploded loudly when mixed 
with an equal bulk of dephlogisticated air, on applying a 
