EXPLOSIVES 385 



tinised. In the product each constituent has its explosive 

 properties modified, and the mass becomes better suited to blast- 

 ing purposes than either ingredient separately. This substance 

 has been largely used under the name " blasting gelatine," and 

 it is otherwise interesting as the forerunner of the various 

 mixtures which have been the subject of experiment and which 

 have resulted in the production of the chief military propellant 

 cordite. It was discovered that not only could the lower nitro- 

 celluloses be gelatinised by nitroglycerine, but that the most 

 highly nitrated cotton could be blended with nitroglycerine if 

 the mixture was treated with a common solvent such as acetone. 



To manufacture cordite the nitroglycerine is poured on to 

 the gun-cotton contained in rubber bags and hand-mixed. The 

 paste produced is then transferred to a large Pfleiderer mixing 

 machine, similar to the machine used in some bakeries for mixing 

 dough, and the requisite quantity of acetone added. After 

 working the mixer for some time, 5 per cent of vaseline is added 

 to increase the stability of the product and lubricate the gun. 

 When gelatinisation is complete the mass is pressed through a 

 die of the requisite size, and the cord which is thus formed 

 wound on a reel, or in the case of the thicker sizes it is cut into 

 suitable lengths. The cordite is then dried slowly to drive off the 

 last traces of acetone. In the case of the larger sticks, containing 

 the smaller quantity of nitroglycerine, 30 per cent, this drying 

 takes about two months. 



It is interesting, says Mr. Macnab, to note the accuracy which 

 has been attained in this manufacture. For rifles, for instance, 

 the velocity prescribed is 2380 foot seconds, with a plus or minus 

 of only 40 feet, and a pressure of 19-5 tons, with a maximum of 

 20 tons per square inch ; for larger guns it may be 2500 foot 

 seconds + 15 foot seconds, and the pressure must not exceed 

 19 tons per square inch. 



In July last (1915) Professor Vivian Lewes 1 of the Royal 

 Naval College, Greenwich, in some lectures delivered before the 

 Royal Society of Arts gave some interesting facts concerning the 

 explosives used in the European war, from which the following 

 condensed account is taken. The shells used in big guns and 

 field artillery may be divided into two main classes, namely 

 shrapnel and high explosive shells. The shrapnel shell, named 

 after its inventor, is a hollow cylindrical projectile packed with 



1 Professor Lewes, unfortunately, died on October 23rd, 1915, 

 2C 



