68 
CAPTAIN NOBLE AND MR. E. A. ABEL ON EIRED GUNPOWDER. 
3. Analysis of the Solid Residue. 
Qualitative analysis indicated that the proportions of the following substances had 
to be determined in the solid residue. 
a. Portion insoluble in water. — This consisted of steel (unavoidably detached from 
the interior of the vessel during removal of the residue) and of small quantities of other 
metals, besides glass, which were used in the construction of the electric igniting 
arrangement. The weight of these substances was deducted from the residue, as foreign 
to the research. 
In addition to these substances, the residue insoluble in water contained generally 
traces of charcoal, besides sulphur, which was combined with iron and portions of the 
other metals, and the amount of which is included in the statement of results as free 
sulphur , together with the proportion which was found, in combination with potassium, 
in excess of the amount required to form the monosulphide. 
b. Portion soluble in water. — In this, the chief portion of the residue, there existed 
the potassium sulphide, sulphocyanate, hyposulphite, sulphate, carbonate, and nitrate, 
besides ammonium carbonate, and, in very exceptional cases, potassium hydrate. The 
estimation of the proportions in which these several constituents existed in the residue 
was conducted as follows : — 
c. Water contained in the residue. — It is obvious that the highly hygroscopic nature 
of the powder-residue rendered it impossible to transfer the product of an explosion 
from the iron cylinder to suitable receptacles for its preservation out of contact with 
the atmosphere without some absorption of moisture, however expeditiously the opera- 
tion was performed. Moreover any water produced during the explosion, or preexist- 
ing in the powder, would necessarily be retained by the solid residue after explosion, 
as the gas remained in contact with a large surface of this powerful desiccating agent 
for some time before it could be collected. In some instances the water was expelled 
from the residue by exposing it for some time to a slow current of hydrogen at 300° C., 
the gas and volatile matters being passed into solution of lead acetate, for the purpose 
of retaining sulphur, and the weight of the dried residue determined. The amount of 
residue, however, was generally too considerable for this operation to be satisfactorily 
performed ; there was therefore no alternative in such cases but to assume that the 
difference between the total weight of the residue and the combined weights of its 
several solid constituents, ascertained in almost every instance by duplicate and check 
determinations, represented the amount of water present in the substance*. 
d. Separation of the portion insoluble in water , and determination of Sulphur in it . — 
The separation was accomplished by thoroughly washing the entire residue, or about 
7 grammes of the ground residue, with well-boiled water until no discoloration was 
produced in the washings by lead acetate. Boiled water was employed to avoid oxi- 
* If discrepancies existed between the results of determination of the several constituents and the check- 
determinations, the water was estimated, as described, in a portion of the residue. 
