130 Mr . Kirwan’s Experiments 
The folution of acetous barofelenite , (that Is, ponderous earth 
diflolved in diftilled vinegar) is rendered brown and turbid by 
this air, but that of marine barofelenite is not altered ; nor are 
the foiutions of other earths. Metallic folutions are afFefted 
by it in the fame manner as by hepatic water, of which I (hall 
treat in the fifth fedtion. 
But of all the tefts of hepatic air, the moft delicate and fen- 
fible is xht folution of Jiher in the nitrous acid. This, according 
as the nitrous acid is more or lefs faturated with filver, becomes 
black, brown, or reddifh brown, by contact with hepatic air 
however mixed with any other air or fubftance. When the 
acid is not faturated, or is in large proportion, the brown or 
black precipitate, which is nothing but fulphurated filver, is 
re-diflblved. 
It ftiould alfo be remarked, that all hepatic air is fomewhat 
diminifhed by long ftanding on mercury, whofefurface is then 
blackened by it. This is particularly the cafe of carbonaceous 
hepatic air, which certainly carries over and volatilizes part of 
the charcoal from which it is extrafted, efpecially that portion 
of air which comes over in the greateft heat ; this it depofits 
on the addition of water. 
SECTION III. 
Of the Action of Hepatic and other Aerial Fluids on each other * 
Six cubic inches of common and fix of hepatic air being 
mixed with each other, and ftanding over mercury for eight 
days, were not in the leaf!: altered in their dimenfions or other- 
wife ; though a diminution of a part might be perceived. 
The mercury was flightly blackened. The event was the fame 
when 
