on Hepatic Air* 14^ 
The precipitation of metallic fubftances by this air is owing 
partly to the union and phlogiftication of the acids by this air, 
and partly to its union with the metals themfelves, for it evi- 
dently unites in mod cafes to both* 
As alkalies and fulphur are known to have an affinity to each 
other* we eafily underftand why hepatic and alkaline airs are 
condenfed when mixed with each other; nor is there any dif- 
ficulty in conceiving why hepatic air is not condenfed by com- 
mon, dephlcgifticated, inflammable, or phlogif|icated airs, or re- 
markably by marine air ; but it Items very extraordinary, that 
Hepatic air and vitriolic air fbould be condenfed, and in great 
meafure converted into fulphur by their mutual a&ion on each 
other, particularly as they both feem nearly of the fame fpe~ 
cies, or at leaft nearly allied to each other. The attra&ion of 
two bodies, thus circumftanced, is certainly very extraordi- 
nary; yet that their union proceeds from attraction feems pretty 
evident, for concentrated vitriolic acid, and particularly vola- 
tile vitriolic acid, precipitates fulphur copiouflv from hepatifed 
water. Volatile vitriolic acid frequently holds fome fulphur in 
folution, as appears from the experiments of Dr, Priestley 
and M. Berthollet ; and hence it depofits fome when it lofes 
its aerial form, or by mere length of time ; but the whole of 
this condenfed air is not turned into fulphur, for the water that 
wafhed the precipitated fulphur took up a quantity of volatile 
acid and fixed air, as has been ffiewn. 
The condenfation of hepatic air by nitrous air feems owing 
to the fame caufe ; for when the nitrous air was in great degree 
deprived of fuperfluous acid, the condenfation of the hepatic 
was much flower ; and that which after all took place feems 
to have been effected by the decompofition of the nitrous air,, 
and the confequent extrication of an acid. 
The • 
