Berzelius on the Sulphurets. 213 
of which is equal to that of the potash; it being understood, 
that we must deduct from the calculation, the quantity of oxygen 
which is present in the potash, combined with sulphuric acid ; 
but this last forms + of the whole quantity of potash ; so that 
the oxygen of the sulphuric acid can constitute only 3 of that 
which is found in the entire potash. To verify this fact, M. Ber- 
zelius prepared hepar with 1 grain of carbonate of potash, which 
was fused in a small retort with 14 times its weight of sulphur*. 
The mixture was dissolved in boiling water, and precipitated 
by muriate of barytes, whence there resulted in two experiments, 
0.421 grains of sulphate of barytes. From calculation, 100 
parts of sub-carbonate of potash transformed in this manner into 
hepar, ought to afford 42.15 parts of sulphate of barytes. These 
experiments then prove, that when the sub-carbonate of potash 
is fused with sulphur, + of the potash serves to form sulphate of 
potash, and the other 3 are converted into sulphuret of potassium; 
a theorem, which we ought henceforth to employ in several cal- 
culations, and whose justness it was right to establish by ex- 
periment, although it was easy to infer it @ proorz. 
I]. Experiments on the different Proportions in which Potassium 
can combine with Sulphur and with sulphuretted Hydrogen. 
1, When sulphate of potash is reduced by hydrogen or carbon, 
there is formed the first degree of sulphuration of potassium, 
that is to say, KS?, which is proportional to the sulphate. Itis 
difficult to obtain it pure. If the operation be made in glass, it 
is attacked; if in platinum, there is formed a higher sulphuret, 
which is mingled with potassuret of platinum. Prepared in 
glass, the sulphuret has a beautiful colour of pale cinnabar, and 
a crystalline fracture. It becomes dark-coloured when we heat 
it; it fuses before it comes to a red heat, and then it is black 
and opaque. When heated in the open air, it does not take 
fire; it is difficult to roast ; but it becomes incandescent at the 
place where it has been kindled. It is extinguished the moment 
that it becomes covered with sulphate of potash. All the proper- 
ties of sulphuret of potassium demonstrate sufficiently, that it is 
a mistake to ascribe the ignition of pyrophorus to the presence 
of the sulphuret of potassium, which certainly has not this vir- 
tue, if it be not united to a more combustible body. It attracts 
humidity from the air, and is resolved into a yellow liquid, 
which on dilution with water, becomes colourless. It is com- 
pletely soluble in alcohol. Placed in contact with water or 
alcohol, it does not become hot; which proves that the affini- 
ties that act in the solution are not very strong. 
To find what is the maaimum of sulphur which can combine 
* The carbonate of potash was prepared out of contact of air, by calcining 
the bi-earbonate in aretort. After weighing, the sulphur was added ; and 
before applying heat a stream of carbonic acid was passed through, to ex- 
pel the atmospheric air. 
P2 
