332 Sir Andrew Noble [March 23, 



Norwegian ballistite. Here, again, is ballistite in the tubular form, 

 and in tbese bottles it is seen in the form of cubes. Here is some 

 gelatinised guncotton in the tubular form, and here are some interesting 

 specimens with which I have experimented, and which up to a certain 

 pressure gave good results, but which exhibited some tendency to vio- 

 lence when that pressure was exceeded. Here also are some samples 

 of the French B.N. powder, consisting of nitrocellulose partially 

 gelatinised and mixed with tannin, and with barium and potassium 

 nitrates. Lastly, I show you here a sample of picric acid, a substance 

 which has been used for many years as a colouring material, but 

 which will be of interest to you, because it is used as the explosive 

 of lyddite shell, concerning which I shall presently have more to say ; 

 it differs from all the other explosives in being, in the crystalline 

 form, exceedingly difficult to light. I fuse, however, in this porcelain 

 crucible a small quantity. I pour a little on a slab, and on dropping 

 a fragment into a red-hot test-tube you see with how much violence 

 the fragment explodes. I also burn a small quantity, and you will 

 observe that unlike guncotton, cordite and ballistite, it is not free from 

 smoke, the smoke in this case being simply carbonaceous matter. You 

 will observe also how much more slowly it burns. 



The composition of these various explosives (although in the case 

 of both cordite and ballistite I have experimented with samples 

 differing widely in the proportion of their ingredients) may be thus 

 stated. 



The guncotton I employed was of Waltham Abbey manufacture, 

 and when dried consisted of 4*4 per cent, of soluble cotton and 

 95*6 per cent, of insoluble — as used it contained 2 '25 per cent, of 

 moisture. 



The service cordite consists of 37 per cent, trinitro-cellulose, with 

 a small proportion of soluble guncotton, 58 per cent, of nitro- 

 glycerine and 5 per cent, of the hydro-carbon vaseline. 



The ballistite I principally used was composed of 50 per cent, 

 dinitro-cellulose (collodion cotton) and 50 per cent, of nitro- 

 glycerine. The whole of the cellulose was soluble in ether alcohol, 

 and the ballistite was coated with graphite. 



The French B.N. powder consisted of nitro-cellulose partly gela- 

 tinised and mixed with tannin, with barium and potassium nitrates. 

 The transformation experienced by some of these explosives is given 

 in Table I., while the pressures in relation to the gravimetric densi- 

 ties of some of the more important are shown in Fig. I. 



The decomjiosition experienced by these high explosives on being 

 fired is of much greater simplicity than that experienced by the old 

 powders, and is, moreover, not subject to the considerable fluctuations 

 in the ultimate products exhibited by them. 



The products of explosion of gun-cotton, cordite, ballistite, etc. are 

 at the temperature of explosion entirely gaseous, consisting of carbonic 

 anhydride, carbonic oxide, hydrogen, nitrogen and aqueous vapour, 

 with generally a small quantity of marsh gas. 



