1822.] of Compounds of Sulphur. 243 
becomes moist in the open air, but not much so. The aqueous 
solution, when mixed with a solution of nitrate or acetate of 
lead, throws down a blood-red precipitate, which slowly changes 
into black, exactly as Berzelius has described. He obtained 
it when mixing nitrate oflead with an aqueous solution of potash 
that had remained during three weeks with a surplus of sulphu- 
ret of carbon.* Even when the solution of the red melted sub- 
stance has assumed the brown colour, it produces a red precipi- 
tate with salts of lead; but, which is curious, the precipitate which 
has been thrown down by a brown solution blackens much 
quicker than that from a red solution. When a piece of the 
melted red substance before it has attracted moisture is thrown 
into a solution of nitrate of lead, the precipitate keeps its colour 
during several days, principally if, after it has been washed with 
water, alcohol is poured on it, and it is then quickly dried. 
When sulphuric, muriatic, or acetic acid is poured on the red 
mass, a violent effervescence takes place, and the smell of sul- 
phuretted hydrogen is perceived, together with some other smell ; 
an oil-like liquid separates, but neither pure sulphur nor pure 
carbon. By being exposed for about 30 hours to the -atmo- 
sphere, it does not lose much of its colour, but in longer time it 
becomes yellow. 
The greyish-black crystalline mass deliquesces quickly when 
exposed to the air, and when tried with tests, it shows free al- 
kali. The aqueous solution is brownish-black without depositing 
any observable powder, but the intensity of its colour is so great 
that it only becomes transparent on being much diluted. When an 
acid is poured in it, it gives out a great quantity of gas which 
seems to be pure sulphuretted hydrogen; a great quantity of 
carbon is precipitated, and but little sulphur. None of the oil-like 
liquid appears. When a solution of it is exposed to the air, it 
remains more than 24 hours without getting turbid ; afterwards 
carbon is precipitated, at last in great quantity, and the liquid 
becomes colourless. 
The black mass deliquesces very readily, and contains free 
alkali. It dissolves easily in water, while a great quantity of 
carbon in flakes is deposed ; the solution is first greenish-yellow, 
and at last, when sulphur has precipitated, it is colourless. When 
an acid is mixed with a recently prepared solution, sulphuretted 
hydrogen is expelled, and a great quantity of sulphur is thrown 
down. I consider the crystalline black mass prepared by heat- 
ing the red substance to be a compound of potassium and a 
kind of sulphuret of carbon; the black uncrystalline mass is a 
mixture of sulphuret of potassium and carbon. 
When the hydrocarbosulphate of potash is exposed to the 
heat of the flame of a candle, it inflames and burns, throwing 
about a great number of brilliant sparks. Two periods may be 
* Afhandlingar i Fysik, Kemie og ee 5 Deel, p, 266, &c, 
R 
