84 
CAPTAIN NOBLE AND MR. E. A. ABEL ON FIRED GUNPOWDER. 
(and other metals derived from the exploding-apparatus) or as polysulphide of potas- 
sium, and which therefore has not entered into the chief reactions, is generally low 
where the hyposulphite is high, which appears to indicate that the latter is also formed 
(at any rate occasionally) by an oxidation of free sulphur following immediately upon 
the first reaction. 
. In the products of decomposition of the powder examined by Bunsen and Schisch- 
koff, which were obtained, at any rate to a considerable extent, by a continued pro- 
cess of oxidation, the conversion of sulphur into the highest product (sulphate) was 
effected to a very great extent, there being no free sulphur and only an exceedingly 
small quantity of sulphide ; but when the deflagration and action of heat were arrested, 
there was still a considerable proportion (7-5 per cent.) of hyposulphite existing in the 
solid residue. The smoke, or portions of the solid products mechanically carried away 
by the gases evolved and afterwards deposited, was found by those chemists also to 
contain as much as 4-9 per cent, of hyposulphite, while neither sulphide nor free 
sulphur were discovered (the sulphate being, on the other hand, considerably higher in 
amount than in the residue itself) ; the gas which escaped contained a very appreciable 
amount of free oxygen, and there was 5 per cent, of nitrate left in the residue when 
the operation was arrested. Here, therefore, the view appears a very probable one 
that the hyposulphite constituted an intermediate product of a reaction following upon 
the production of sulphide in the first instance. In. Linck’ s experiment, conducted in 
the same way, the process of deflagration being, however, apparently arrested at an 
earlier stage, more than twice the amount of hyposulphite found by Bunsen and 
Schischkoff existed in the residue, while there were still nearly 6 per cent, of sulphide 
and 0'5 per cent, of sulphur unoxidized, and a considerably smaller amount of sulphate 
formed. This difference between the results of two experiments conducted on the 
same plan may certainly be partly ascribed to the difference in the composition of the 
two gunpowders experimented with, as that used by Linck was nearly of normal com- 
position, and contained nearly 3 per cent, more sulphur, and quite 3 per cent, less salt- 
petre, than Bunsen and Schischkoff’s powder ; yet this very circumstance appears to 
support the view that, at the first instant of explosion, sulphide is formed in consider- 
able proportion, its immediate oxidation and the nature and extent of that oxidation 
being regulated by the proportion of oxygen which is liberated at the time that the 
sulphide is formed, the same also applying to the proportion of sulphur which at the 
moment of explosion does not combine with potassium to form sulphide. 
Potassium hyposulphite is stated to decompose at about 200° C. ; but it is evidently 
formed at very much higher temperatures ; and the experiments of Bunsen and Schisch- 
koff and of Linck demonstrated that it may remain undecomposed, or may continue 
to be produced, in powder-residue which is maintained at a high temperature. 
We ourselves have exposed portions of powder-residue obtained in our experiments 
for lengthened periods to the heat of a Siemens furnace (1700° C.), and have still 
detected small quantities of hyposulphite in the material after such exposure. 
