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40 rounds of black powder, and 249 rounds of cordite (58 per cent. nitro-glycerine) and was still in excellent condition, and showed very little sign of action, and also a 12-lb. B.L. gun that had been much used and was in no wise injured. [Footnote A: The gun-cotton used contains 12 per cent. of soluble gun-cotton, and a nitrogen content of not less than 12.8 to 13.1 per cent.] [Illustration: Fig. 37 Scale, 1 inch = 1 foot. Single Strand Reel.] [Illustration: FIG. 38.--"TEN-STRANDING."] In some experiments made by Captain Sir A. Noble,[A] with the old cordite containing 58 per cent. nitro-glycerine, a charge of 5 lbs. 10 oz. of cordite of 0.2 inch diameter was fired. The mean chamber crusher gauge pressure was 13.3 tons per square inch (maximum 13.6, minimum 12.9), or a mean of 2,027 atmospheres (max. 2,070, min. 1,970). The muzzle velocity was 2,146 foot seconds, and the muzzle energy 1,437 foot tons. A gramme of cordite generated 700 c.c. of permanent gases at 0 deg. C. and 760 mm. pressure. The quantity of heat developed was 1,260 gramme units. In the case of cordite, as also with ballistite, a considerable quantity of aqueous vapour has to be added to the permanent gases formed. A similar trial, in which 12 lbs. of ordinary pebble powder was used, gave a pressure of 15.9 tons per square inch, or a mean of 2,424 atmospheres. It gave a 45-lb. projectile a mean muzzle velocity of 1,839 foot seconds, thus developing a muzzle energy of 1,055 foot tons. A gramme of this powder at 0 deg. C. and 760 mm. generates 280 c.c. of permanent gases, and develops 720 grm. units of heat. [Footnote A: _Proc. Roy. Soc._, vol. lii., No. 315.] In a series of experiments conducted by the War Office Chemical Committee on Explosives in 1891, it was conclusively shown that considerable quantities of cordite may be burnt away without explosion. A number of wooden cases, containing 500 to 600 lbs. each of cordite, were placed upon a large bonfire of wood, and burned for over a quarter of an hour without explosion. At Woolwich in 1892 a brown paper packet containing ten cordite cartridges was fired into with a rifle (.303) loaded with cordite, without the explosion of a single one of them, which shows its insensibility to shock. With respect to the action of cordite upon guns, Sir A. Noble points out that the erosion caused is of a totally different kind to that of black powder. The surface of the barrel in the case of cordite ap
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