216 Progress of Foreign Science. 
potassium, a quantity which is consequently present in the 
22.28 grains of sulphuret of potassium obtained. It was there- 
fore united in it, with 10.464 grains of sulphur; but 
11.816 : 10.464 :: 100 : 88.55. 
Four atoms of sulphur would make 82.12. There is here 
the notable difference 6.43. He at first took this combination 
for that of KS4; but having mixed a part of the solution with 
nitrate of copper, there formed to his great surprise a precipi- 
tate of sulphuret of copper, with the disengagement of sulphu- 
retted hydrogen gas. Other metallic salts produced the same 
effect ; consequently, the solution contained more sulphuretted 
hydrogen, than had been formed by the oxidation of the potas- 
sium. Mingled with an acid, it became cloudy indeed, and 
assumed a milky aspect; but when the sulphur fell, it was seen 
to be only a very slight deposit; and the remainder of this 
substance escaped in the form of sulphuretted hydrogen gas. 
It was clear, therefore, that the combination effected in the 
dry way, was composed of sulphuret of potassium, and sul- 
phuretted hydrogen; now, if we suppose that it was a double 
sulphuret, KS? + 2K2S*, that is to say, that the potash and 
hydrogen, were united to an equal quantity of sulphur, 100 
parts of potassium ought to have combined with 82.12 parts of 
sulphur, and 2.60 of hydrogen, together = 84.72 parts. The 
excess actually found is undoubtedly due to the contact of air, 
which, in oxidizing the hydrogen at its expense, has formed a 
higher degree of sulphuration, whence has proceeded the preci- 
pitate produced by the acids. 
It was interesting then to know if the neutral hydrosulphuret 
of potash is a compound of the same kind. With this view 
M. Berzelius saturated a portion of pure potash with sulphuret- 
ted hydrogen gas, and raised the mixture to ebullition ; passing 
at the same time through the apparatus a stream of hydrogen, 
till the whole excess of the sulphuretted hydrogen had been 
expelled. A portion of this solution was precipitated by the 
muriate of copper, added drop by drop. The precipitate col- 
lected on a filter, well washed, dried and heated in a retort, 
till nothing remained but sulphuret of copper at the mini- 
mum, weighed 1.82 grains. ‘The solution, after the remainder 
of the copper had been separated by the sulphuretted hydro- 
gen, was evaporated to dryness, and afforded 1.71 grain of 
muriate of potash; there was therefore 2 atoms of copper for 
1 of potash. We thence see, that in order to form a neutral 
hydrosulphuret, the potash takes a quantity of sulphuretted 
hydrogen, in which the hydrogen is double the quantity neces- 
sary to form water with the oxygen of the potash; and that 
this hydrosulphuret, in the dry state, may be represented like 
the preceding combination, by KS? + 2H®*S. 
* Misprinted inthe Annales. It ought to-be 7H?S, 
