HISTORY OP PROPELLANTS 33 



increased. The powder without sulphur had its potential 

 energy increased by about 13 per cent., while that with 

 increased sulphur was decreased by 9 per cent. 



The early methods for testing the potential energy and 

 uniformity of gunpowder were very rude, and permitted 

 in this country powders to be passed into the service which 

 showed great variations in potential energy. 



My attention was called to this point in 1860, when, 

 being then an associate member of the Ordnance Select 

 Committee and carrying out experiments for that body, 

 I found that the variation in the energy developed by new 

 powders of different makes occasionally amounted to 25 

 per cent. 



The variation admitted at the present day in passing 

 propellants is about 2.8 per cent. 



The early improvements in the old gunpowder were due 

 to the labors of Major Rodman, U. S. A., who seems to 

 have been the first to appreciate the importance of a suit- 

 able and uniform density of the powder, but also by the 

 introduction of prismatic powder showed that it was pos- 

 sible considerably to reduce the very high and variable 

 pressures which were common in the old guns, pressures 

 which would not be permitted in the much stronger guns 

 of the present day. He was also the inventor of a most 

 ingenious instrument for determining the pressure devel- 

 oped by the explosion of the charge in the chambers or 

 bores of guns, and Major Rodman's work was continued in 

 this country by the labors of the first explosive committee, 

 who not only determined with great accuracy the pressures 

 of the propellants and the velocity of the projectiles at all 

 points of the bore, but also increased the velocity by over 

 220 foot-seconds, thus increasing the energy developed by 

 about 33 per cent., while the maximum pressure was re- 

 duced by about the same percentage a matter of very 

 great importance in the case of all, but especially of 

 breech-loading guns. 



But I fear I have detained you too long with the old 

 3 



