1909] on Guncotton and Nitroglycerine. 439 



required rate of combustion could Ije obtained. The use of smoke- 

 less powders, manufactured in this way, was very soon extended to 

 all natures of ordnance. 



The next step in the development of smokeless powders was the 

 combination of nitroglycerine with nitrocellulose. The first powder 

 of this type was the " ballistite " of Alfred Nobel, patented l)y him 

 in the year 1888. The original ballistite was composed of equal 

 parts of nitroglycerine and of soluble nitrocellulose, a variety of gun- 

 cotton soluble in nitroglycerine, and no solvent was therefore required 

 in its preparation, although a certain proportion of camphor was used 

 to promote the solution of the nitrocellulose. Another form of nitro- 

 glycerine-nitrocellulose explosive is the British service powder, 

 cordite, which originally consisted of nitroglycerine 58 parts, gun- 

 cotton, insoluble in nitroglycerine, 37 parts, and mineral jelly, a 

 product of the distillation of crude petroleum, 5 parts. To effect 

 the gelatinisation of the guncotton, the solvent acetone, obtained 

 indirectly from the destructive distillation of wood, is employed. 

 The result of subjecting nitrocellulose, in suitable machines, to the 

 action of nitroglycerine or of solvents, of which there are several 

 suitable ones besides acetone, is to destroy its fibre and convert it 

 into a gelatinous mass, in which condition it can be formed into any 

 desired shape. Where solvents are used to produce this result, they 

 remain in the mass during subsequent operations,and are finally driven 

 off by means of heat. The resulting products, somewhat incorrectly 

 termed " powders," which are manufactured in a variety of forms, such 

 as grains and flakes of different shapes, ribbons or strips, solid cords, 

 tubes, etc., vary in consistence with the quantity of nitroglycerine they 

 contain. The more nitroglycerine present, the softer the powder ; 

 pure nitrocellulose powders being hard to brittleness. 



For practical purposes modern smokeless powders are of two 

 types :— 



1. Those consisting entirely of nitrocellulose, and termed "nitro- 

 cellulose powders." 



2. Those consisting of a mixture of nitrocellulose and nitro- 

 glycerine, known as " nitroglycerine powders." 



Opinions differ somewhat as to the relative merits of these two 

 types ; in this country the latter type is preferred. Their character- 

 istic features are, briefly, as follows : — 



A nitroglycerine powder is more powerful than a nitrocellulose 

 powder, and the more nitroglycerine present the more powerful the 

 explosive. Therefore, for equal ballistics, a smaller charge of the 

 former than of the latter is required, and, consequently, the chamber 

 capacity and the size and weight of the breech mechanism is reduced ; 

 on the other hand, the higher the proportion of nitroglycerine the 

 higher is the temperature of combustion, and the greater the erosive 

 effects on the surface of the bore of the gun. 



The presence of nitroglycerine in an explosive allows of the more 



Vol. XIX. (No. 103) 2 g 



