PRESIDE>T S ADDRESS SECTION B. yy 



perforated prisms, on the other hand, develop an increasing surface 

 as it burns away, thereby keeping up a constant supply of speed- 

 producing gas, and accelerating the speed of the projectile. In the 

 P2 powder, thereiore, we have actually a decreasing evolution of 

 gas, whereas in the prism powder the order of things is reversed, 

 as shown by the diagram.* 



In burning it is probable that the prisms break up across the 

 lines of least i-esistance, as shown in Fig. 1., ««, bb, and so on, 

 thereby producing many new surfaces for combustion and fully 

 developing the jDrogressive character of the powder. 



The prism form has been adhered to, but the Black Prismatic 

 powder has been superseded by a still slower burning powder, 

 which differs somewhat in composition from it in so far as it con- 

 tains only 3 per cent, of sulphur and as much as 3 per cent, of 

 moisture. It is known as S.B.C , or slow burning. " Cocoa 

 Powder." 



This new form of prismatic powder brought about a complete 

 revolution in gunnery. With a slower burning powder the lengthen- 

 ing of the gun followed as a m.atter of course, the chambering was 

 increased, and the muzzle loader was converted for obvious reasons 

 into a breechloader. " Cocoa powder " may be looked upon as 

 the connecting link between the obsolete black powder and the 

 modern smokeless powders. Although it cannot be looked upon 

 as a smokeless powder, in the latest sense of the term, yet the 

 smoke produced by its combustion is white, and disperses very 

 quickly. It is probable that the evidence of this, brought forward 

 in experiments with heavy ordnance and quick-firing gurs, served, 

 in the first instance, to attract attention to the necessity of reducing 

 the production of smoke to the least possible point, and finally 

 led to the conviction among naval and military experts that the 

 substitution of smokeless powder for black powder in artillerj^ and 

 small arms was a matter of the first importance. In accordance 

 with this view, the energies of scientists, both at home and abroad, 

 have, during the last few years, been devoted to the task of bringing 

 this undertaking to a successful issue. 



SMOKELESS POWDERS. 



Guncotton in every form. Picric acid, and Nilro-cellulose, have, 

 during the last twenty years, been subjected to experiment with 

 the object of forming smokeless powders, but the problem, simple 

 as it appears, presented almost insurmountable difficulties, and 

 baffled the energies and knowledge of the most scientific chemists, 

 so that it is only within the last few years that any approach to 

 success has been made ; and this success has been due to recent 

 discoveries in chemistry. 



• Taken from " A Lecture delivered before the R. A. Institution on January 23rd, 1893," by 

 Lieut.-Col. F. W\ J. Barker, R.A. 



