1900.] Some Modem Explosives. 329 



WEEKLY EVENING MEETING, 



Friday, March 23, 1900. 



His Grace tiie Duke op Northumberland, E.G. F.S.A., 

 President, in the Chair. 



Sir Andrew Noble, K.C.B. F.R.S. M. Inst. C.E. M.R.I. 



Some Modern Explosives. 



Nearly thirty years ago, in the Eoyal Institution, I had the 

 honour of describing the great advances which had then recently 

 been made both in our knowledge of the phenomena which attend 

 the decomposition of gunpowder, and in its practical application to 

 the purposes of artillery. 



I described the uncertainty which up to that date had existed 

 as to the tension developed by its explosion ; the estimates varying 

 enormously from the 101,000 atmospheres (about 662 tons on the 

 square inch) of Count Rumford to the 1000 atmospheres (6 ■ 6 tons 

 per square inch) of Robins, or, taking more modern estimates, 

 from the 24,000 atmospheres (158 tons per square inch) of Piobert 

 and Cavalli to the 4300 atmospheres (about 29 tons per square 

 inch) of Bunsen and Schischkoff. 



These uncertainties were, I think I may say, set to rest by certain 

 experiments carried out both in guns and close vessels at Elswick, by 

 the labours of the Explosive Committee appointed by the War Office, 

 and by researches conducted by Sir F. Abel and myself. These 

 researches were conducted on a large scale, with the view of repro- 

 ducing as nearly as possible in experiment the conditions that exist 

 in the bore of a gun. You may judge of the magnitude of the 

 experiments when I tell you that I have fired and completely re- 

 tained in one of my cylinders a charge of no less than 28 lbs. of 

 ordinary powder. 



The result of the discussion of the whole series of experiments 

 led to the following conclusions : 



1. That the tension of the products of combustion at the moment 

 of explosion when the powder practically filled the space in which 

 it is fired — that is, when the density is about unity — is a little over 

 40 tons on the square inch, or about 6400 atmospheres, 



2. Although changes in the chemical composition of powder, and 

 even changes in the mode of ignition, cause a very considerable 

 change in the metamorphosis experienced in explosion — as evidenced 

 by the proportions of the products, the quantity of heat generated, and 

 the quantity of permanent gases produced, being materially altered— 

 it is somewhat remarkable that the tension of the products in relation 



Vol. XVI. (No. 94.) z 



