3892.] Pressure developed by some New Explosives. 125 



a. Ordinary pebble powder of the Service. A charge of 12 Ibs. 

 was used ; this charge gave rise to a mean pressure of 15'9 tons per 

 square inch (maximum, 16'8 ; minimum, 14*9), or a mean of 2424 

 atmospheres (maximum, 2566 ; minimum, 2277) as determined by 

 the crusher gauge in the powder chamber. It gave to a 45-lb. pro- 

 jectile a mean muzzle velocity of 1839 ft. -sees., thus developing a 

 muzzle energy of 1055 ft. -tons. A gramme of pebble powder at a 

 temperature of C. and a barometric pressure of 760 mm. generates 

 280 c.c. of permanent gas, and develops 720 gramme units of heat. 



b. Amide powder, consisting of 40 per cent, of potassic nitrate, 

 38 per cent, of ammonia nitrate, and 22 per cent, of charcoal. The 

 charge in this case was 10 Ibs. 8 ozs., and the mean crusher gauge 

 pressure was 15'3 tons per square inch (maximum, 16'4 ; minimum, 

 14*2), or a mean of 2332 atmospheres (maximum, 2500; minimum, 

 2165) ; the muzzle velocity with^the same projectile was 2036 

 ft.-secs., and the muzzle energy 1293 ft. -tons. A gramme of amide 

 powder generates 400 c.c. of permanent gases, and develops 821 units 

 of heat. 



c. Ballistite. With this true smokeless powder the charge was re- 

 duced to 5 Ibs. 8 ozs., the sides of the cubes being O f 2 inch. The 

 mean crusher-gauge pressure was 14'3 tons per square inch (maxi- 

 mum, 14'5 ; minimum, 14'1), or a mean of 2180 atmospheres 

 (maximum, 2210; minimum, 2142). The muzzle velocity was 

 2140 ft.-secs., and the muzzle energy 1429 ft. -tons. A gramme of 

 ballistite generates 615 c.c. of permanent gases, and gives rise to 

 1365 gramme units of hea.t. 



d. With the fourth explosive, Cordite, a charge of 5 Ibs. 10 ozs. of 

 0'2 inch diameter was fired. The mean chamber crusher-gauge pres- 

 sure was 13'3 tons per square inch (maximum, 13'6 ; minimum, 12'9), 

 or a mean of 2027 atmospheres (maximum, 2070 ; minimum, 1970). 

 The muzzle velocity was 2146 ft.-secs., and the muzzle energy 1437 

 ft .-tons. A gramme of cordite generates 700 c.c. of permanent gases 

 at C. and 760 mm. of barometric pressure. The quantity of heat 

 developed is 1260 gramme units. In the case of this explosive, as well 

 as in that of ballistite, a considerable quantity of aqueous vapour has 

 to be added to the permanent gases. 



The results of these observations are graphically given in the 

 figure. The ordinates show both the positions at which the pres- 

 sures were determined, and the magnitudes of these pressures. On 

 the axis of abscissae is shown the travel of the shot in feet. 



Each curve is deduced from the mean of three* complete rounds, 



* Since these experiments were carried out, a second set of induction coils has 

 been added, so that a single round gives simultaneously the times both at the 

 breech and muzzle plugs. 



