288 On the Composition of the Alkaline Sulphurets. [Ocr. 
formed in glass, it is acted upon; if in platina, a stronger 
sulphuret is formed, which is mixed with a compound of platina 
and potassium. When prepared in glass, the sulphuret has a 
pale cinnabar colour, and a crystalline fracture. It becomes 
dark when itis heated; it fuses at a heat below redness; and then 
it is black and opaque. Heated with excess of air, it does not 
inflame. All the properties of sulphuret of potassium sufficiently 
show that it is erroneous to attribute the ignition of pyrophorous 
to its presence ; for it does not possess this power unless com- 
bined with a still more combustible body. It attracts moisture 
from the air, and dissolves into a yellowish fluid, which, when 
diluted with water, becomes colourless. It dissolves perfectly 
in alcohol. When moistened with water or alcohol, it does not 
become hot, which shows that the affinities acting in the solution 
are not very strong. 
In order to discover the maximum of sulphur which combines 
with potassium, 1 fused 0-782 of a gramme of carbonate of potash 
with 1-5 gramme of sulphur in a small retort ; the mixture was 
exposed to a moderate heat until the excess of sulphur was 
expelled. It then weighed 1-267 gramme. In the upper part 
of the retort, there was a small portion of hepar of a finer red 
colour, which, when dissolved in water, deposited sulphur. Its 
quantity was, however, so small, that its weight was not deter- 
mined. The salt employed contained 0-5326 gramme of potash, 
of which one-fourth, equal to 0°13315 gramme, had formed sul- 
phate of potash with 0:0458 gramme of sulphur, and with the 
oxygen of the remaining three-fourths. To determine the quan- 
tity of sulphur which was combined with the reduced potassium, 
the weight of the potash and that of the sulphur in the sulphuric 
acid, together 0°5784, must be deducted from 1-267. This quan- 
tity is 0°6886, which was combined with 0:3315 of potassium ; 
that is to say, 100 parts of potassium had combined with 207-7 of 
sulphur ; but this number is nearly equal to 10 atoms; for the 
weight of 
Ke 80'S 23100: cue 2 
It appears then that 100 parts of subcarbonate of potash 
absorb as a maximum 93°9 parts of sulphur. The finer colour of 
the hepar, which was deposited upon the upper part of the retort, 
and which on solution deposited sulphur, induced me to think 
that a sulphuret in a still higher degree was formed, but which 
could not exist at a red heat, and which water decomposed, 
separating a portion of its sulphur. 
(To be continued.) 
