DR. H. DEBUS ON THE CHEMICAL THEORY OF GUNPOWDER. 
535 
boiled in order to expell the air, and the solution divided into two equal parts. One 
of these parts was saturated with sulphuretted hydrogen in an atmosphere of hydrogen 
and then mixed with the other, and the solution of potassic sulphide, so obtained, 
digested with powder of sulphur in sufficient quantity to produce pentasulphide. The 
analysis of this liquid gave the following results :— 
10 cub. centims. diluted with previously boiled water were acidulated with hydric 
chloride and heated to the boiling point. A precipitate of 1*094 grms. of sulphur was 
obtained. The filtrate evaporated to dryness and ignited, the dry residue moistened 
with hydric chloride, and then raised to a red heat gave 1*387 grms. of potassic chloride, 
corresponding to 0726 grm. of potassium. On the assumption that 1 atom of sulphur 
had escaped as sulphuretted hydrogen, the liquid, according to these determinations, 
contains sulphur and potassium in the proportion of 4*67 atoms of the former to 2 atoms 
of the latter. 
10 cub. centims. of the sulphide mixed with a solution of zinc sulphate, and the 
filtrate tested with an iodine solution in presence of some starch required 0*2 cub. 
centim. of the iodine liquid in order to produce a blue colour. 1 cub. centim. of the 
iodine solution corresponded to 1 cub. centim. of a solution of sodium hyposulphite 
containing 24'8 grms. of the salt in 1 litre. 
Therefore, 10 cub. centims. of the polysulphide of potassium contain : 
0*0038 grm. potassic hyposulphite 
2*119 grms. potassic polysulphide. 
To check these numbers, Mr. Cowper at my request dissolved the zinc sulphide in 
hydric nitrate of 1*5 sp. grav., and determined the zinc and the sulphur in the solution 
according to the usual methods. 
He obtained : 
Sulphur . . . . 1*285 grms. 
Zinc. 0*556 grm. 
or for every atom of zinc 4*69 atoms of sulphur. 
180 cub. centims. of the solution of potassic polysulphide were digested in a 
hermetically closed flask with pure and previously ignited cupric oxide at common 
temperatures. The liquid assumed a brown colour, which still could be observed after 
two days’ digestion. The flask was now placed in water of 35° C., whereupon the 
colour rapidly disappeared. The contents of the flask were now placed upon a filter, 
the cupric oxide and sulphide well washed, and filtrate and wash water united and 
kept in a closed bottle. 
I. 25 cub. centims. of the liquid so prepared, neutralised with acetic acid, mixed 
with some starch solution, required 24*6 cub. centims. of iodine solution for the 
production of the blue colour. 
25 cub. centims. in another experiment required 24 cub. centims. iodine solution. 
25 cub. centims. in a third experiment required 24*2 cub. centims. iodine solution, 
MDCCCLXXXII, 3 z 
