1879.] 



Researches on Explosives. 



129 



(whether primary or secondary) is conclusively demonstrated by a 

 thorough examination into the results given in their first memoir, they 

 have been anxious to obtain, if possible, some further decisive 

 evidence as to the probable proportions of hyposulphite actually exist- 

 ing in the residues furnished by the explosion of gunpowder in closed 

 vessels. They, therefore, introduced some variations in the methods 

 of collecting and preparing the solid products for analysis, of which 

 the following is an outline. 



In two experiments with K.L.Gr. and pebble powders, the solid pro- 

 ducts, collected as rapidly as possible, were divided into two equal 

 parts, the one consisting of the upper, the other of the lower, part of 

 the mass. These portions were again equally divided ; one-half, com- 

 posed of large lumps, was as rapidly as possible (being but a few 

 moments exposed to air) sealed up in dry bottles freed from oxygen ; 

 the other half of each was ground finely and exposed to the air for 

 forty-eight hours. 



In both experiments the lower ground portion heated very decidedly 

 more than the upper part, the tendency to heat being abnormally high 

 in the case of the pebble residue ; a thermometer inserted into the 

 ground mass indicated a temperature of 315° C. After half an hour's 

 exposure the deposit cooled very rapidly. 



The products obtained in these two experiments w r ere submitted to 

 partial examination, the chief object being to see to what extent the 

 proportions of hyposulphite and sulphide varied in the upper and 

 lower portions of the residue, and the extent to which they were 

 affected by the great difference in the mode of treatment sustained by 

 the different portions of one and the same residue. 



The numerical results obtained show that, in both experiments, 

 those portions of the residue which were exposed to the air only for a 

 few seconds, and of which but small surfaces were thus exposed (as 

 they were collected in large lumps) contained hyposulphite ranging 

 in amount from 5 to 8" 5 per cent. Those portions which were 

 specially treated for the purpose of favouring to the utmost the 

 formation of hyposulphite from sulphide through atmospheric agency, 

 contained, as was to be expected, very large proportions of the former, 

 while the latter had entirely disappeared in three out of the four 

 portions of very finely pulverised residue. In the fourth, however, 

 even after its free exposure to air for forty-eight hours, there still 

 remained nearly 3 per cent, of sulphide. ISTow, as in no single 

 instance in the entire series of the experiments did any accidental 

 circumstances occur, which even distantly approached the special con- 

 ditions favourable to the oxidation of the sulphide which were 

 introduced into these particular experiments, the authors consider 

 themselves justified in arriving at the conclusion, that the total 

 absence of sulphide in the residues furnished by the fine-grain powder 



VOL. XXIX. K 



