1907.] on Fifty Years of Explosires. 457 



raised from about 1600 f.s. to about 2100 f.s., while the energies 

 developed were increased by about 75 per cent., causing an immediate 

 reconstruction both of guns and mountings. 



From all these powders, upon which I have spent much time, I 

 part with regret. They belong to the past, but I am not sure that 

 I can say the same with respect to the Amide powders. 



You will remember I pointed out to you that, with the Amide 

 powder with which I experimented, there was an increase of potential 

 energy over that of the Service powders of about 65 per cent., but, 

 in that powder, less than half of the potassium nitrate had been 

 replaced by ammonium nitrate, this smaller quantity being doubtless 

 taken on account of the deliquescent properties of the latter salt ; 

 but that powder I have been able to keep, without difficulty, in 

 Service powder cases for more than eighteen years, and if there be 

 no practical difficulty in manufacturing a powder in which the whole 

 of the potassium nitrate is replaced by ammonium nitrate, a much 

 greater energy might be obtained, and it must be remembered that 

 the Amide possesses the advantage of low erosion. 



Some three or four years ago Sir AV. Crookes suggested to me a 

 method of protecting these powders, which both he and I have tried 

 with success, and we may, therefore, hope that the difficulty to which 

 I have referred may possibly be overcome. 



I now turn to modern explosives, and the points to which I wish 

 to direct your attention are : — 



Firsts the tensions of the gases of the various propeUants at the 

 moment of explosion for all densities from "05 to •5. 



Second^ to ascertain the variation in the proportion of the re- 

 sultant gases which accompanies a change in the density of the 

 explosive fired. 



Third, to determine the volume of permanent gases and aqueous 

 vapour generated by explosion. 



Fourth, to determine the corresponding units of heat generated 

 by the explosion, and thence to arrive at the approximate temperature 

 of explosion. 



Fiftli; to ascertain the time of combustion of the explosives under 

 different pressures, and of different dimensions of cords, tubes, etc. 



Sixth, to find the rapidity with which the explosives part with their 

 heat to the walls of the vessels in which they are fired. 



I proceed to describe the apparatus employed to obtain the data I 

 have enumerated. 



In the diagram I have thrown on the screen, "A" is the vessel 

 in which the explosion takes place, " B " is the plug closing the 

 vessel, on which also is shown the arrangement by which the gas, 

 when desired, is allowed to pass at a feeble pressure either into the 

 gasometer, or, at pleasure, into the gas tubes, and which, before the 

 experiment, are filled with mercury, the stop cocks above and below 

 beins: closed. 



