8 Sir Frederick Ahel [Jan. 31, 



of cxj)losion, and the dense white smoke which it produces, consists 

 in part of extremely finely divided potassium carbonate which is a 

 component of the solid products, and, to a great extent, of potassium 

 sulphate produced chiefly by the burning of one of the important 

 solid products of explosion, potassium sulphide, when it is carried in 

 a fine state of division into the air by the rush of gas. 



With other explosives, which are also smoke-producing, the 

 formation of the smoke is due to the fact that one or other of the 

 products, although existing as vaj)our at the instant of its develop- 

 ment, is immediately condensed to a cloud composed of minute liquid 

 particles, or of vesicles, as in the case of mercury vapour liberated 

 upon the explosion of mercuric fulminate, or of the aqueous vapour 

 produced upon the ignition of a mixture of ammonium nitrate and 

 charcoal, or ammonium nitrate and picric acid. 



Until within the last half-dozen years, the varieties of gunpowder 

 which have been applied to war purposes in this and other countries 

 have exhibited comparatively few variations in chemical composition. 

 The proportions of charcoal, saltpetre, and sulphur, employed in their 

 production, exhibit slight diiferences in difi'erent countries, and tbese, 

 as well as the character of the charcoal used, its sources and method 

 of production, underwent but little modification for very many years. 

 The same remark applies to the nature of the successive operations 

 pursued in the manufacture of black powder for artillery purposes in 

 this and other countries. 



The replacement of smooth-bore guns by rifled artillery, which 

 followed the Crimean war, and the increase in the size and power of 

 guns consequent upon the application of armour to ships and forts, 

 soon called for the pursuit of investigations having for their object 

 the attainment of means for variously modifying the action of fired 

 gunj)owder, so as to render it suitable for the different calibres of 

 guns, whose full power could not be effectively, or in some instances 

 safely, develoj^ed by the use of the kind of gunj)owder previously 

 employed indiscriminately in artillery of all known calibres. 



In order to control the violence of explosion of gunpowder, by 

 modifying the rapidity of transmission of explosion from particle to 

 particle, or through the mass of each individual j)article, of which the 

 charge of a gun is composed, the accomplishment of the desired results 

 was, in the first instance, and indeed throughout practical investigations 

 extending over many years, sought exclusively in modifications of the 

 size and form of the individual masses composing a charge of powder, 

 and of their density and hardness ; it being considered that, as the 

 proportions of saltpetre, charcoal and sulphur, generally emjiloyed 

 in the production of gunpowder, very nearly correspond to those 

 required for the development of the greatest chemical energy by those 

 incorporated materials, it was advisable to seek for the attainment of 

 the desired results by modifications of the physical and mechanical 

 characters of gunpowder, rather than by any modification in the 

 proportions and chemical characters of its ingredients. 



