For firing blank cartridges cordite chips containing no vaseline is used. The rate at which cordite explodes depends in a measure upon the diameter of the cords, and the pressure developed upon its mechanical state. The sizes of cordite used are given by Colonel Barker, R.A., as follows:-- For the .303 rifle .0375 inch diameter. " 12 Pr. B.L. gun .05 " " " .075 " " 4.7-inch Q.F. gun .100 " " 6-inch Q.F. gun .300 " " heavy guns .40 to .50 " For rifles the cordite is used in bundles of sixty strands, in field-guns in lengths of 11 to 12 inches, and the thicker cordite is cut up into 14-inch lengths. Colonel Barker says that the effect of heat upon cordite is not greater as regards its shooting qualities than upon black powder, and in speaking of the effect that cordite has upon the guns in which it is used (R.A. Inst.) said that they had at Waltham Abbey a 4.7-inch Q.F. gun that had fired 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.]