NATURE 



[May 31, 1900 



I had cordite of the same dimensions prepared with varying 

 proportions of nitro-glycerine and guncolton. The nitro- 

 glycerine being successively in the proportions of 60, 50, 40, 30, 

 20 and 10 per cent., and with each of these cordites I deter- 

 mined the following points : — 



(i) The quantity of permanent gases generated. 



^2) The amount of aqueous vapour formed. 



(3) The heat generated by the explosion. 



'Fig. 6. -Energy in foot tons ; heat in 



. ; gas in c.c. ; erosion in inches ; pressure in tons. 



(4) The erosive effect of the gases. 



(5) The ballistic energy developed in a gun, and the corre- 

 sponding maximum pressure. 



(6) The capacity of the cordite to resist detonation when 

 fired with a strong charge of fulminate of mercury. 



The results of these experiments were both interesting and 

 instructive. 



To avoid wearying you with a crowd of figures, I have placed 

 on Fig. 6 the results of the first five series 

 of experiments. 



On the axis of abscissae are placed the 

 percentages of nitro-glycerine, while the 

 ordinates show the quantities of the gases 

 .generated, the amount of heat developed, 

 the erosive effect of the explosive, the bal- 

 listic energy exhibited in a gun, and the 

 •maximum gaseous pressure. 



You will note that with the smallest 

 'proportion of nitro-glycerine the volume 

 of permanent gases is a maximum, and 

 that the volume steadily decreases with 

 the increase of nitro-glycerine. On the 

 other hand, the heat generated as steadily 

 increases with the nitro-glycerine, and if 

 we take the product of the quantity of heat 

 and the quantity of gas as an approximate 

 measure of the potential energy of the 

 explosive, the higher proportion of nitro- 

 glycerine has an undoubted advantage ; 

 but in this case, as in the case of every 

 other explosive with which I have experi- 

 mented, the potential energies differ less 

 than might be expected from the changes 

 in transformation, as the effect of a large 

 quantity of gas is to a great extent com- 

 pensated by a great reduction in the quan- 

 tity of heat generated. 



This effect is, of course, easily explained, and was very 

 strikingly exhibited in the much more complicated transforma- 

 tion experienced by gunpowders of different compositions, a 

 long series of which were very fully investigated by Sir F. Abel 

 and myself. 



Looking at this diagram you will have observed that the 

 energy developed in the gun is very much smaller with the 



NO. 1596, VOL. 62] 



smaller proportions of nitro-glycerine, but if you will look at 

 the corresponding maximum pressure-curve you will note that 

 the pressures have decreased nearly in like proportion. Hence it 

 is probable that the lower effect is mainly due to a slower com- 

 bustion of the cordite, and it follows that this effect may be, to 

 a great extent, remedied by increasing the rate of combustion 

 by reducing the diameter of the cordite to correspond with the 

 reduction in the quantity of nitro-glycerine. 



To test this point I caused to be manu- 

 factured a second series of cordites of the 

 same composition, but with the diameters 

 successively reduced by •03, as you see with 

 the samples I hold, and this diagram (Fig. 

 7) shows at a glance the result. The 

 energies you see are, roughly, practically 

 the same, but if you look at the pressure- 

 curve you will observe that I have ob- 

 tained a curve in which, on the whole, 

 the pressures vary in the contrary direction, 

 that is to say, in this case the pressures 

 increase as the nitro-glycerine diminishes. 



Taking the two series into account, they 

 show that by a proper arrangement of 

 amount of charge and diameter of cord it 

 would be possible to obtain the same bal- 

 listics and approximately the same pressure 

 from any of the samples I have exhibited to 

 you. 



But I have to draw your attention to 



another point. From the curve showing 



the quantities of heat you will note that in 



passing from 10 per cent, nitroglycerine 



to 60 per cent., the heat generated has 



increased by about 60 per cent. But here 



is the curve indicating the corresponding 



amount of erosion, and you will see that 



while the quantity of heat is only greater by 



i about 60 per cent., the erosion is greater by nearly 500 per cent. 



i These experiments entirely confirm the conclusion at which I 



have previously arrived, viz. that heat is the principal factor in 



1 determining the amount of erosion. 



In experimenting with a number of alloys of steel, the greatest 

 resistance was shown by an alloy of steel with a small propor- 

 tion of tungsten, but the difference between the whole of these 

 amounted only to about 16 per cent. 





Fig. 7. — Energy in foot tons ; pressure in tons. 



The whole of these cordites were, as I have mentioned, sub- 

 jected to detonation tests. None of them, so far as my experi- 

 ments went, exhibited any special tendency in this direction. 



I will now endeavour to describe to you a most interesting 

 and important series of experiments which, I regret to say, is a 

 long way from completion. 



The objects of these experiments were (i) to ascertain the 



