346 M. Berzelius on the [Nov. 
red heat, with more carbonate of potash than it is capable of 
decomposing, it forms K S®, It follows also trom this experi- 
ment, that 100 parts of subcarbonate of potash are decomposed 
at a low red heat, by 58°22 of sulphur, and it forms then KS + 
3K S*. 
When this compound is mixed with an excess of carbonate of 
potash, and heated to redness, it boils slowly, and gives out 
some carbonic acid gas ; but as at this temperature the glass is 
acted upon, it is difficult to determine whether the evolution of 
carbonic acid gas arises from this cause, or from the formation 
of a lower sulphuret of potassium. The experiment was repeated 
in «small platina crucible, in which 3:7 grammes of carbonate 
of potash were mixed with 0°5 gramme of sulphur. The crucible 
was placed in another, and surrounded with powdered charcoal, 
and these were put into a third crucible ; they were all perfectly 
closed with lids. The object of this arrangement was to prevent 
the access of atmospheric air during cooling. The mixture was 
heated for a long time at a very low temperature to prevent the 
loss of sulphur which might occur during the extrication of the 
carbonic acid gas; the heat was afterwards gradually increased 
to redness, and kept up to this degree for half an hour. The 
weight of the cooled crucible was diminished by 0364 gramme, 
caused by the disengagement of carbonic acid gas, and corres- 
ponding to 0°78 gramme of carbonate of potash. Of this quan- 
tity, one-fourth, or 0:195 gramme, had combined with 0:066 er. 
of sulphur to form sulphate of potash, so that 0-434 of sulphur 
were combined with 0:485 gr. of potassium ; but 
48°5 : 48:4 :: 100 : 80°95 
Then 82 would indicate 4 atoms, and the difference may arise 
from the disengagement of sulphur which might have accompa- 
nied the carbonic acid gas at the commencement of the opera- 
tion, when its escape could not be discovered, nor the heat 
regulated. 
The result of this experiment is then, that when K S® mixed 
with carbonate of potash is exposed to a red heat, an additional 
portion of carbonate is decomposed, and A S* is formed, a 
degree of combination in which the affinities of the sulphur and 
carbonic acid are counterbalanced ; 100 parts of carbonate of 
potash form then with 43°78 parts of sulphur 
KS°+3K S 
The hepar obtained by this operation is green, a colour which 
evidently does not belong to the sulphuret of potassium. When 
it had been dissolved in water, it deposited a spongy substance, 
of a reddish-brown colour, which was hydrosulphuret of platina. 
The crucible had lost 0°3 of a gramme in weight. There was, 
therefore, formed a double sulphuret of potassium and platina 
