VOL. LXXVI.j PHILOSOPHICAL TRANSACTIONS. 73 



turbid, and in a few weeks deposits most of it in the form of sulphur, though 

 the bottle be ever so well stopped, or stand inverted in water or mercuryo Yet 

 water no way decomposes hepatic air by absorbing it; for the part left unab- 

 sorbed by a quantity of water is absorbable by a larger quantity of water, and 

 burns like other hepatic air. Heat does not expel this air from water, till car- 

 ried to the degree of ebullition. 



Of all the tests of hepatic air, the most delicate and sensible is the solution 

 of silver in the nitrous acid. This, according as the nitrous acid is more or less 

 saturated with silver, becomes black, brown, or reddish brown, by contact with 

 hepatic air however mixed with any other air or substance. When the acid is 

 not saturated, or is in large proportion, the brown or black precipitate, which 

 IS nothing but sulphurated silver, is re-dissolved. 



Of the Action of Hepatic and other Aerial Fluids oneach other. — Six cubic inches 

 of common and 6 of hepatic air being mixed with each other, and standing over 

 mercury for 8 days, were not in the least altered in their dimensions or otherwise; 

 though a diminution of a -p^-g- part might be perceived. The mercury was slightly 

 blackened. The event was the same when 3 measures of common and 1 of hepatic 

 air were used. Water took up the hepatic air. No fixed air was found. Five mea- 

 sures of hepatic and 5 of dephlogisticated air, so pure that one measure of it and 

 1 of nitrous air made only -rV of a measure, remained unaltered for 8 days, the mer- 

 cury only being blackened. No fixed air was produced, nor the dephlogisticated 

 air phlogisticated. When the mixture was fired, it went off all at once with a 

 loud report. Four measures of phlogisticated and 4 of hepatic air remained 

 unaltered for l6 days: water then took up the hepatic, and left the phlogisticated 

 air. Four measures of inflammable and 4 of hepatic air remained unaltered for 

 6 days. Two measures of hepatic and 2 of marine acid air suffered no diminu- 

 tion in 3 days. The mercury on which they stood was not blackened. Water 

 took up both, and precipitated the solution of silver black. The same quan- 

 tity of hepatic and fixed air remained 4 days without any sensible diminution. 

 Four measures of water absorbed the greater part of both, had an hepatic smell, 

 precipitated lime from its solution, and also silver, as usual. The residuum 

 extinguished a candle. 



But vitriolic, nitrous, and alkaline airs had very remarkable effects on he- 

 patic air. Two measures of hepatic being introduced to 2 of vitriolic air, a whitish 

 yellow deposition immediately covered both the tops and sides of the jar, and 

 both airs were, without any agitation, reduced to little more than 1 measure; 

 but the opacity of the incrusted glass prevented the ascertaining the diminution 

 with precision. Hence he repeated this experiment more at large, in the follow- 

 ing manner. To 5 measures of vitriolic air (each measure containing a cubic 

 inch) he added 1 of hepatic air. In less than a minute, without any agitation, 



VOL. XVI. L 



