538 
DR. H. DEBUS ON THE CHEMICAL THEORY OF GUNPOWDER. 
At my request, Mr. Cowper digested solutions of the other sulphides of potassium 
with cupric oxide and examined the products for potassium hyposulphite. He found 
that in a solution of potassic tersulphide (K 2 S 3 ) nearly in one of potassic disulphide 
about and in one of potassic sulph-hydrate about -f-j of the potassium appears after 
treatment with cupric oxide as hyposulphite. All these experiments lead to the con¬ 
clusion that the potassic hyposulphite found in solid powder residues by Bunsen and 
Schischkoff’s method had been formed during the analysis of the said residues, and 
was not one of the original products of explosion. This conclusion is supported by 
the observation of Pape/'' according to which potassic hyposulphite is decomposed 
at 225° 0. into sulphate and pentasulphide of potassium. 
At the conclusion of my experiments in July 1879, I communicated the results to 
Mr Abel, and he has since then confirmed my observations. 
Noble and Abel say at the end of their second memoir (Phil. Trans., 1880, p. 277), 
“that although it would seem that in certain cases and under certain exceptional 
circumstances potassium hyposulphite does exist as a secondary, it exists in no case as 
a primary product, and should not, therefore, be reckoned among the normal constituents 
of pow T der residues.” 
Wishing to obtain a clear conception of the mode of action of cupric oxide in the 
analysis of a powder residue, I instituted the following experiments :— 
6*157 grms. potassic sulphate, and 8*541 grms. of potassic carbonate were dissolved 
in 100 cub. centims. of water; the solution filled the space of 103*5 cub. centims. 
10 cub. centims. of this liquid were mixed with 5 cub. centims. of a solution con¬ 
taining : 
Potassium. 0*389 grm. 
Sulphur. 0*498 „ 
or 3*12 atoms of sulphur for every 2 atoms of potassium. 
The solution so prepared was then digested for two days with previously ignited 
cupric oxide in a well-stoppered bottle, at ordinary temperatures. 
The mixture appeared brown, but became decolorised at 35° C. 
The contents of the bottle were placed upon a filter; the black oxide and sulphide 
were well washed with boiling water, and both, filtrate and wash water united, were 
kept in a stoppered bottle. They filled the space of 578 cub. centims. 
Ill cub. centims. of the filtrate required 3*7 cub. centims. of the iodine solution. 
192 cub. centims. of the filtrate required 6*3 cub. centims. iodine liquid. Hence, the 
entire filtrate contained 0*3623 grm. of potassic hyposulphite. 
91 cub. centims. of the filtrate acidulated with hydric chloride, boiled for some 
minutes, separated from precipitated sulphur by filtration, and mixed with baric 
* Pogg. Ami., Bel. exxii., p. 408. 
