on Hepatic Air • 145 
It precipitates both vitriol of copper, and the nitrous fait of 
copper, red and brown. 
Tin in aqua regia gives a yellow ifh precipitate; gold a dilute 
yellow and reddifh brown; platina a fleffi- coloured precipitate; 
and regulus of antimony a yellowifh red. 
Silver is precipitated black ; and fo is lead both from the 
nitrous and acetous acids. 
Sublimate corrofve appeared for an inftant red ; but foon after 
its precipitate appeared partly black and partly white. 
The nitrous folution of bifmuth affords alfo a precipitate? 
partly black, partly white, and partly reddifh brown, and of 
a metallic appearance; that of cobalt is alfo black or deep 
brown. 
Arfnical folution s give yellow precipitates more or lefs red ; 
but thofe of %inc only a dirty white. 
All thefe colours vary in fome degree, according as the 
liquors are more or lefs faturated previous to and after their 
mixture, and the time they have flood together. 
SECTION VII. 
Of the Confitution of Hepatic Air . 
From an attentive confi deration of the above experiments, 
which I purpofely difengaged from all theory, it is difficult to 
conclude, that hepatic air confifts of any thing elfe than ful« 
phur itfelf, kept in an aerial ftate by the matter of heat. 
Every attempt to extra£l inflammable air from hepatic air, 
when drawn from materials that previoufly contained nothing 
inflammable, namely, from alkaline or calcareous hepars, 
Vol. LXXVI. U proved 
