on Hepatic Air » 129 
With refpeft to folubility in water , hepatic airs extracted 
from different materials differ conflderably. In the temperature 
of 66°, water diffolves, by flight agitation, two-thirds of its 
bulk of alkaline or calcareous hepatic air, extradited by marine 
acid ; three-fourths of its bulk of martial hepatic air, extradited' 
by the fame acid; eight-tenths of that extradited by means of 
the concentrated vitriolic acid, or the dilute nitrous or faccha- 
rine acids in the temperature of 6o° ; feven-tenths of fedative 
hepatic air; nine-tenths of acetous hepatic air, and of that 
afforded by oil of olives ; and its own bulk of that produced 
from a mixture of fugar and fulphur. In general, I imagined 
that which required moft heat for its production to be moft 
foluble : though in fome inftances, particularly that of acetous 
hepatic air, that circumftance does not take place. 
But the moft remarkable phenomenon attending the union 
of hepatic air with water is, that it is not permanent- Even 
water, out of which its own air had been boiled, in a few 
days after faturation with hepatic air grows turbid, and in a 
few weeks depofits moft of it in the form of fulphur, though 
the bottle be ever fo well flopped, or ftand inverted in 
water or mercury. Yet water no way decompofes hepatic air 
by abforbing it ; for the part left unabforbed by a quantity of 
water is abforbable by a larger quantity of water, and burns 
like other hepatic air. Heat does not expel this air from water, 
until carried to the degree of ebullition. 
No fpecies of hepatic air, which I have examined, precipi- 
tates lime from lime-water , except the carbonaceous ; and even 
this fcarcely produces a fenfible precipitation, unlefs a large 
quantity of it be made to pafs through a frnall quantity of 
lime-water. 
Vo L. LXXVI. S The 
