1879.] 



Researches on Ed'jrfosives. 



127 



(in regard to the chief products only) assumed to be attainable from 

 the introduction, on the one hand of excess of saltpetre, on the other 

 of excess of charcoal, into the composition of powder, M. Berthelot 

 passes to what he terms the accessory products and, excluding from 

 these potassium hyposulphite, which he deals with separately, he first 

 gives two equations to account for the production of sulphocyanide ; 

 then two more to explain the existence of ammonium sesqui-carbonate 

 (which he believes to be formed by the action of water vapour on 

 potassium cyanide) ; the existence of sulphuretted or free hydrogen is 

 explained by two more equations, and marsh-gas is assumed to result 

 from " the pyrogenous decomposition of the charcoal in the powder." 

 Lastly, an equation is given to account for the possible formation of 

 traces of hyposulphite, which Berthelot however regards entirely as a 

 product formed during the collection and analytical treatment of the 

 solid residue, but which the authors nevertheless believe they now 

 conclusively prove to be formed in very notable quantities before the 

 solid residue can have undergone alteration from external causes. 



It will be seen from the foregoing- outline of M. Berthelot 's theo- 

 retical explanation of the chemical changes involved in the metamor- 

 phosis of gunpowder, that the simplest form of expression which he 

 can give to the formation of . the products of explosion consists in the 

 incorporation of nine or ten distinct reactions, occurring simultaneously 

 but in very variable proportions, which have to be supplemented by 

 three or four other chemical equations, by which the formation, during 

 the process of cooling of certain products believed to be secondary, is 

 explained. Now, although such speculations as the above are un- 

 questionably interesting, and, it may be added, of a nature which 

 must occur to those who desire to give some kind of definite explana- 

 tion, for purposes of elementary instruction, of the chemical changes 

 involved in the explosion of powder, the authors fail to see that, beyond 

 this, they do more than afford the strongest confirmation of the cor- 

 rectness of their conclusion, that "no value whatever can be attached 

 to any attempt to give a general chemical expression to the metamor- 

 phosis of a gunpowder of normal composition." 



With reference to the potassium hyposulphite, which, in the 

 analyses of the solid products published in the first memoir, ranged 

 from 3 to 35 per cent, (the monosulphide being generally small in 

 amount when the proportion of hyposulphite was high), the authors 

 reply to M. Berthelot's suggestion, that its existence may be only 

 ascribable to the oxidation of sulphide during the operation of 

 removal from the explosion-vessel and of analysis, by pointing out the 

 nature of the precautions taken to avoid oxidation of sulphide in the 

 collection of the solid residue, and its preservation for analysis, and 

 by admitting the formation of some hyposulphite during the unavoid- 

 able exposure to air of the residues while they were being removed 



