3819.] extracted from Pyrites at Fahlun. 405 
employed this reagent to separate it from the great mass of 
liquid which I had obtained by washing the sulphureous matter 
not attacked by the nitra-muriatic acid. Sulphuretted hydrogen 
produces a fine orange precipitate, which, towards the end, 
becomes a dirty yellow. The filtered hepatic liquor still con- 
tained sulphates of iron, zinc, and lime. 
a. The precipitate being well washed and pressed was mixed 
with nitro-muriatic acid, and digested for some time. The solu- 
tion at first was very rapid ; but it gradually diminished. There 
remained an impure sulphur which could not be entirely dissolved 
except by reiterated digestions. 
b. The acid liquor was decanted and water added to it. A 
copious white precipitate fell. Water was added as long as the 
Liquid became muddy, and the whole was then thrown on the 
filter. The precipitate being well washed and examined b 
means of the blow-pipe produced at first a strong smell of horse- 
radish. There remained a white powder, which, by means of 
soda and a little borax, was reduced inte a metallic globule, 
which possessed all the properties of tin. It produced hydrogen 
gas when treated with mumatic acid ; it was corroded but not 
dissolved by nitric acid, &c. The precipitate obtained, being 
well dried, was put into a small glass retort and heated to redness. 
There sublimed into the neck of the retort a matter crystallized 
in needles, and the oxide which remained had lost the property 
of giving out the smell ef horseradish when treated by the blow- 
pipe. The sublimate had a strong acid taste; but pure, like 
that of muriatic or sulphuric acid, and was easily dissolved in 
water. It was an acid having selenium for its radical, and of 
which we shall examine the properties hereafter. . 
The liquid from which water had precipitated the seleniate of 
tin was mixed with muriate of barytes as long as any precipitate 
was produced. It was filtered, and evaporated till it began to 
exhale abundant vapours of muriatic acid. It was then put into 
aretort, and distilled to dryness. The retort was then exposed 
to a higher temperature. There sublimed into the upper part 
and neck of the retort a white substance in the form of long 
four-sided needles ; and at the bottom of the retort remained a 
little white matter with red stains. 
d, The sublimate was removed. It had a taste at first acid, 
and afterwards metallic. I considered it as a volatile nitrate or 
muriate with excess of acid. I took a portion of it, which I 
mixed with zinc filings, and distilled the mixture in a curved 
glass tube. Selenium sublimed without any mixture of muriate 
of zinc, or the disengagement of any gas. [ digested the mass, 
which remained unsublimed in water, and the liquid, though 
mixed with nitrate of silver, remained clear. Of course, it eon- 
tained no muriatic acid. Consequently the sublimate was pure 
selenic acid; but as it had a metallic taste of which no trace 
could be observed in the acid obtained by the decomposition of 
