MODERN EXPLOSIVES 23 



no acid taste can be detected, boiling in water till free from 

 action on litmus, reducing to pulp in a hollander, and 

 finally, the thorough washing of the pulp by more water. 

 If the product now satisfies the tests of purity, sufficient 

 alkali limewater, whiting, and caustic soda is added to 

 leave from one to two per cent, in the finished guncotton. 

 The pulp is drawn up into a vessel from which it can be 

 run off in measured quantities into molds fitted with per- 

 forated bottoms, the water being drawn off by suction from 

 below, and finally, a low hydraulic pressure is brought to 

 bear on the semi-solid mass. The blocks are taken to the 

 press house and submitted to a pressure of some five tons 

 per square inch, after which the finished block will contain 

 from 12 to 16 per cent, of water. 



From its chemical reactions guncotton must be regarded 

 as an ether of nitric acid, a view first suggested by 

 Beehamp. The point of ignition of the substance has been 

 found to vary considerably, ranging from 136 to 223 C., 

 this difference being probably due to variations in composi- 

 tion. Good guncotton usually ignites between 180 and 

 184 C. The combustion is extremely rapid when fired in 

 loose unconfined masses, so rapid, in fact, that it may be 

 ignited on a heap of gunpowder without affecting the latter. 

 When struck between hard surfaces guncotton detonates, 

 but usually only in that portion which is subjected to the 

 blow. The volume of permanent gases evolved by the 

 explosion of guncotton, as stated by different observers, has 

 varied greatly. Macnab and Ristori give for nitrocellulose 

 (13-30 per cent, nitrogen) 673 c.c. per gram, calculated 

 at c. and 760 mm. Berthelot estimates the pressure 

 developed by the detonation of guncotton (sp. gr. 1-1) under 

 constant volume as 24,000 atmospheres, or 160 tons per 

 square inch. 



Various attempts have been made to adapt guncotton for 

 use in guns, but the tendency to create undue pressure led 

 to its abandonment. In 1868, Mr. E. 0. Brown, of Wool- 

 wich, showed that wet guncotton could be detonated by the 



