200° An Analysis of two Mineral 
sulphur not washed, and form them into a paste 
with a little water, and let them remain together 
some hours: put the paste into water and filtrate : 
_this water now strikes a purple colour with galls. 
Now, common sulphur is always contaminated with 
a little sulphuric acid; and (as neither hepatic gas 
nor oxygenated salt are here concerned) the effect 
must be attributed to the acid and the sulphur. If 
this water be evaporated, it leaves a matter which 
does not deliquesce; but which emits the same smell 
as the residuum of the hepatised solutions. To shew 
that the acid is necessary to the production of the 
purple colour, let the sulphur be well washed with 
distilled water before it is mixed with the iron; and 
it will be found, that no such colour can be now 
produced. The following fact seems to prove, that 
sulphur may be retained in water in the form neither 
of sulphur nor of hepatic gas: it is an additional 
proof, how essentially the oxygenated differs from’ 
all the common salts of iron. I saturated a diluted 
solution of oxygenated muriat of iron, which scarce- 
ly affected nitrat of silver, with hepatic gas. A 
white precipitate fell, but so minute that it was im- 
possible to collect it, nor did it destroy the tran- 
sparency of the water: hence, I think it probable, 
that, if the salt were quite perfect, it would not be. 
sensibly affected by hepatic gas. I now boiled the 
liquor, to expel the gas, till it wholly lost its hepatic 
smell. The liquor was again tried with nittat of 
