i es 
ADDRESS. 27 
by aiming at an approach to identity in the characters of the individual 
grains or masses. 
When our attention was first actively directed to the modification of 
the ballistic properties of powder, the subject had already been to some 
extent dealt with, in the United States, by Rodman and Doremus, and the 
latter had proposed the employment, in heavy guns, of charges consisting 
of large pellets of prismatic form. While this prismatic powder, which 
was first used in Russia, was being perfected, and extensively applied 
there as well as in Germany and England, the production of powder- 
masses more suitable, by the comparatively gradual nature of their ex- 
plosion, for the very large charges required for the heavy artillery of the 
present day, was actively pursued in Italy, and by our own Government 
Committee on Explosives, the outcome of exhaustive practical investi- 
gations being the very efficient Fossano powder, or poudre progressif 
of the Italians, and the boulder- and large cylindrical-powders produced 
at Waltham Abbey. 
Researches carried out by Captain Noble and myself, some years ago, 
with a series of gunpowders presenting considerable differences in com- 
position, indicated that decided advantages might be secured, for heavy 
guns especially, by the employment of such a powder as would furnish a 
comparatively very large volume of gas, its explosion being at the same 
time attended by the development of much less heat than in the case of 
ordinary black powder. In the course of these researches much light 
was thrown npon the causes of the wearing or erosive action of powder- 
explosions upon the inner surface of the gun, an action which, especially 
in the larger calibres of artillery, produces so serious a deterioration of the 
arm that the velocity of projection and accuracy of shooting suffer consider- 
ably, the wear being most considerable where the products of explosion, 
while under the maximum pressure, can escape between the projectile and 
the bore. The great velocity with which the very highly-heated gaseous 
and liquid (fused solid) products of explosion sweep over the heated sur- 
face of the metal, gives rise to a displacement of the particles composing 
the surface of the bore, which increases in extent as the latter becomes 
roughened, and thus opposes increased resistance ; at the same time, the 
high temperature to which the surface is raised reduces the rigidity of 
the metal, and its consequent power of resisting the force of the gaseous 
torrent; and, lastly, some amount of chemical action upon the metal, by 
certain of the highly-heated, non-gaseous products of explosicn, contri- 
butes towards an increase in the erosive effects. Experiments made upon 
a large scale by Captain Noble with powders of different composition, 
and with other explosives, have afforded decisive evidence that the explo- 
sive agent which furnishes the largest proportion of gaseous products, 
_and the explosion of which is attended by the development of the smallest 
amount of heat, exerts least erosive action. 
Some eminent German gunpowder-manufacturers, who were at this 
