Experimental and Applied 309 



combustion may be brought under perfect control, and they 

 therefore become available as propulsive explosives, i.e. in 

 artillery and small arms. In these directions they are rapidly 

 displacing the charcoal or black powders which have done so 

 much service to the human race in the past centuries ! A 

 special advantage of these nitrocellulose powders from the 

 military point of view is that, owing to their perfect combustion 

 to gaseous products, their explosion is a ' smokeless ' one : 

 hence their general and popular designation. The basis of these 

 'powders' is a mixture of nitroglycerin and * nitrocellulose.' 

 The nitrates of cellulose are gelatinised by nitroglycerin, and 

 by varying the proportions homogeneous plastic mixtures of 

 varying consistency are obtained. With small proportions of 

 the cellulose compounds, 7-8 p.ct., a gelatinous mass is ob- 

 tained, known industrially as ' Blasting Gelatine.' With lower 

 proportions, gradations of consistency are obtained in the 

 mixture which is the basis of explosives of the * Gelignite ' 

 class. With the cellulose nitrates increased to 40-50 p.ct. a 

 semi-solid product is obtained, which is worked up into threads 

 or ribands and constitutes the military smokeless powders 

 (' ballistite,' 'cordite,' &c.). The product resulting from the 

 mixture of these two ' high explosives ' burns quietly when 

 ignited, and, burning from the surface^ the combustion is 

 perfectly under control, and can be easily regulated to avoid 

 detonation. A second class of ' powders ' is made by mixing 

 the nitrocellulose and a certain proportion of barium nitrate 

 with a smaller proportion of camphor or nitrobenzene to allow 

 of their being worked up to a suitable form. Such are the 'E.G.,' 

 'S.S.,' and other ' sporting' powders. In many of the latter the 

 nitrocelluloses employed are prepared by nitrating the celluloses 

 of Class B (supra) isolated by the processes of the papermaker j 

 in some cases also nitrated lignocelluloses are employed. 



These industries are in a highly developed condition, the 



