1822.] of Compounds of Sulphur. 245 
passing through different shades, it assumes a brownish-black 
colour, and the heat being increased, it becomes completely 
black, and whilst exhibiting the phenomena of combustion. The 
gas does not contain any carbonic acid, and seems to be the 
new gaseous compound of carbon and sulphur. 
The substance remaining when the carbosulphuret has thus 
been exposed to a red heat is a mixture of a metallic sulphuret 
and carbon. I have reasons for considering the brown mass be- 
fore it has been exposed to a red heat, as a new metallic car- 
bosulphuret, either with another kind of carbosulphuret than that 
which exists in the precipitated substance, or with the same, but 
in less quantity. The carbosulphuret of mercury shows the 
same phenomena, except that at a pretty high temperature, a 
substance is sublimed which resembles cinnabar, and a black 
scaly mass remains which is charcoal. 
The precipitate obtained from sulphate of zinc and the salt of 
potash consists, when dry, of small greenish-white heavy grains, 
soluble both in water and alcohol; however, in a much greater 
quantity in the latter. The alcoholic solution furnishes, when 
evaporated, white opaque globular masses. When newly preci- 
pitated, it is easily decomposed by sulphuric and muriatic acid, 
and furnishes an oil-like liquid, similar to that which is procured 
from the hydrocarbosulphate of lime by a similarprocess. When 
heated, this compound of zinc is changed into a mass of a pretty 
intense green colour, which, when an acid is poured on it, gives 
out with violent effervescence a gaseous compound of sul- 
phuretted hydrogen, and another peculiar gas. Paper, previously 
moistened with a solution of lead, becomes, when exposed to 
these gases, on different places spotted blood-red and black ; 
the first being the prevailing colour. 
The hydrocarbosulphuric acid is insoluble in water, or at least 
nearly so ; its specific gravity is greater than 1-0. It may easily 
be procured by pouring a mixture of one part of sulphuric acid 
and three-fourths of a part of water on the hydrocarbosulphate 
of potash, and adding, in a few seconds, a great quantity of 
water. The acid soon collects on the bottom of the vessel as a 
completely transparent almost colourless oil; it must be quickly 
washed with water until it ceases to give a precipitate with a so- 
lution of muriate of barytes. The acid may almost entirely be 
freed from water by decantation. 
When litmus paper is brought into this acid, it becomes in- 
stantly red ; if the paper remains exposed to the air, it becomes 
partially yellow and white. The smell of this acid is com- 
pletely different from that of sulphuret of carbon; its taste is 
acid, and strongly astringent. Exposed to the air, it is soon 
covered with a yellowish-white coating. It is easily inflamed, 
and when burned, gives out the smell of sulphurous acid. It is 
decomposed by heat. 
It is easily dissolved by a solution of potash in water, which 
