1890.] on Smokeless Explosives. 11 



same time, the effect of the high temperature to which the surface is 

 raised is to reduce its rigidity and power of resisting the force of the 

 gaseous torrent, and lastly some amount of chemical action upon the 

 metal, by certain of the highly heated non-gaseous products of 

 explosion, contributes towards an increase in the erosive effects. A 

 series of careful experiments made by Captain Noble with powders 

 of different composition, and with other explosives, afforded decisive 

 evidence that the explosive agent which furnished the largest pro- 

 portion of gaseous products, and the explosion of which was attended 

 by the development of the smallest amount of heat, exerted least 

 erosive action. 



It is probable that important changes in the composition of 

 powders manufactured by us for our heavy guns would have resulted 

 from those researches, but in the meantime, two eminent German 

 gunpowder manufacturers had occupied themselves independently, 

 and simultaneously, with the important practical question of pro- 

 ducing some more suitable powder for heavy guns than the various 

 new forms of ordinary black powder, the rate of burning of which, 

 especially when confined in a close chamber, was, after all, reduced 

 only in a moderate degree by the increase in the size of the masses, 

 and by such increase in their density as it was practicable to attain. 

 The German experimenters directed their attention not merely to an 

 alteration of the proportions of the powder ingredients, but also to 

 a modification in the character of charcoal employed, and the success 

 attending their labours in these directions led to the practically 

 simultaneous production, by Mr. Heidemann at the Westphalian 

 Powder Works, and Mr. Diittenhofer at the Eottweil Works near 

 Hamburg, of a prismatic powder of cocoa-brown, colour, consisting 

 of saltpetre in somewhat higher proportion, of sulphur in much lower 

 proportion, than in normal black powder, and of very slightly burned 

 charcoal, similar in composition to the charcoal (cJiarhon roux) which 

 Violette, a French chemist, first produced in 1847 by the action of 

 superheated steam upon wood or other vegetable matter, and which 

 he proposed for employment in the manufacture of sporting powder. 

 These brown prismatic powders (or " cocoa-powders," as they were 

 termed from their colour), are distinguished from black powder not 

 only by their appearance, but also by their very slow combustion in 

 open air, by their comparatively gradual and long-sustained action 

 when used in guns, and by the simple character of their products of 

 explosion as compared with those of black powder. As the oxidising 

 ingredient, saltpetre, is contained, in brown or cocoa powder, in larger 

 proportion relatively to the oxidisable components sulj)hur and char- 

 coal than in black powder, these become fully oxidised, while the 

 products of explosion of the latter contain, on the other hand, larger 

 proportions of unoxidised material, or of only partially oxidised pro- 

 ducts. Moreover, there is produced upon the explosion of brown 

 powder a relatively very large amount of water-vapour, not merely 

 because the finished powder contains a larger proportion of water than 



