440 Colonel Sir Frederu' L. Nathan [Jan. 29, 



easy and rapid elimination of the solvent used in manufacture, and of 

 moisture, a small quantity of which is always present in nitroglycerine 

 and guncotton. The sooner this is attained the better, because the 

 longer the time that the powder is being heated in order to dry it, 

 the more likely is its chemical stability to be affected. ]\Ioreover, it 

 is a well-established fact that with nitrocellulose powders it is im- 

 possible to remove the volatile matter Avith anything like the same 

 completeness as can be done in the case of nitroglycerine powders. 

 The consequence is that the slow evaporation from nitrocellulose 

 powders of the residual volatile matter which takes place in store 

 tends to produce changes in their physical character, and renders them 

 in course of time lial)le to alter in ballistic properties, and even to 

 develop dangerous pressures in the gun. 



Nitroglycerine powders are cheaper than nitrocellulose powders,, 

 weight for weight, and even more so for equal ballistic effects. 



The original cordite, the manufacture of which commenced in 

 1890, contained a high proportion of nitroglycerine, 58 per cent., 

 and the erosion produced, especially in large guns, was considerable. 

 This led to experiments being carried out at Waltham Abbey, with a 

 view to the production of a less erosive explosive, and the final result 

 was the introduction into the service, in 1901, of a modified cordite 

 known as " cordite M.D." in which the percentage of nitroglycerine 

 is reduced to 80 per cent., so that the composition becomes : nitro- 

 glycerine 30 per cent., guncotton 65 per cent., and mineral jelly 

 5 per cent. 



The constants of explosion of cordite and cordite M.D., deter- 

 mined at the Royal (ninpowder Factory, some little time ago, are as 

 follows : — 



Jleat of Kxplo- Total Gases 



„ , . Density of sion at Constant vv„t^r r.c^, .',= Teniperaturr 



^-^Pl— ,^^^^ Volume. Water ,,^0,^60^0. ^^P'--" 



Gaseous. 



Calories per Gram. cc. per Gram. °C. 



Cordite ... 0-2 1156 871 2663 



Cordite M.D. . 0-2 965 920 2374 



An inspection of these figures show^s that the alteration in proportions 

 of the explosive ingredients results in a decrease in the heat of 

 explosion of about \i\\ per cent., and an increase in the volume of 

 gases of about 5J per "cent., whilst there is a decrease of 289° C. in 

 the temperature of explosion. 



x\s would therefore be expected the erosion produced by cordite 

 JM.D. is very much less than that produced by the original cordite 



