m Hepatic Air . itt 
The above experiment feems to Ihew that liver of fulphur 
will not yield hepatic air without the addition of an acid ; and 
I believe this to be true when the experiment is made in the 
dry way, and nearly fo in the moift way ; for having added 
200 grains of fulphur to a concentrated folution of ftrong 
cauftic vegetable alkali, by a ftrong and long-continued heat I 
obtained only i cubic inch of hepatic air ; yet it is well known, 
that a ftrong folution of liver of fulphur conftantly emits an 
hepatic fmell, even in the temperature of the atmofphere ? 
and the fubftance fo emitted contains fo much hepatic air as to 
difcolour filver and lead, and even their folution s ; which 
Ihews, that an incomparably fmali quantity of this air is 
capable of producing this effect To difcover whether this 
extrication of hepatic air might be caufed by the depofition of 
fixed air from the atmofphere, I threw feme pul verified calca- 
reous hepar into aerated water, and by the application of heat 
endeavoured to obtain hepatic air, but in vain : and, indeed, 
the very circutnftance that the hepatic fmell, and its effeCis, 
are always ftrongeft the firft inftant that a bottle of the 
hepatic folution is opened, feems to indicate that fixed air is no 
way concerned in its production. 
The heft liver of fulphur is made of equal parts of fait of 
tartar and fulphur; but as about one-fifth of the fait of tartar 
confifts of air which efcapes during the operation, it feems, 
that the proportion of fulphur predominates in the refulting 
compound; yet as fome of the fulphur alfo fublimes and bums, 
it is not eafy to fix the exact proportion. 100 grains of the 
beft, that is, the reddeft liver of fulphur, afford, with dilute 
marine acid, about 40 cubic inches of hepatic air, in the tem- 
perature of 6o° : a quantity equivalent to about 13 grains of 
fulphur, as will be feenin the fequeL 
Vol. LXXVL R 
The 
