134 Dr. Ure on Gunpowders 



angles removed, by causing it to revolve in a close reel or cask 

 turning rapidly round its axis. This vessel resembles some- 

 what a barrel-churn, and is frequently furnished inside with 

 square bars parallel to its axis, to aid the polish by attrition. 



The gunpowder is finally dried, which is now done generally 

 with a steam heat, or in some places by transmitting a current 

 of air, previously heated in] another chamber, over canvass 

 shelves, covered with the damp grains of gunpowder. 



5. On the Proportion of the Constituents. 



A very extensive suite of experiments to determine the pro- 

 portions of the constituents for producing the best gun- 

 powder, was made at the Essonne works, by a commission of 

 French chemists and artillerists, in 1794. 



Powders in the five following proportions were prepared : 



Nitre. Charcoal. Sulphur. 



1 76 14 10 Gunpowder of Bale. 



2 76 12 12 Gunpowder works of Grenelle. 



3 76 15 9 M. Guyton de Morveau. 



4 77.32 13.44 9.24 Idem. 



5 77.5 15 7.5 M. Riffault. 



The result of more than two hundred [discharges with the 

 proof-mortar shewed that the first and third gunpowders 

 were the strongest, and the commissioners in consequence 

 recommended the adoption of the third proportions. But a 

 few years thereafter it was thought proper to substitute the 

 first set of proportions, which had been found equal in force to 

 the other, as they would have a better keeping quality, from 

 containing a little more sulphur and less charcoal. More 

 recently still, so strongly impressed have the French govern- 

 ment been with the high value of durability in gunpowders, 

 that they have returned to their ancient dosage of seventy-five 

 nitre, twelve and a half charcoal, and twelve and a half sulphur. 

 In this mixture, the proportion of the substance powerfully 

 absorbent of moisture, viz., the charcoal, is still further reduced, 

 and replaced by the sulphur, or the conservative ingredient. 



If we inquire how the maximum gaseous volume is to be 

 produced from the chemical reaction of the elements of nitre 

 on charcoal and sulphur, we shall find it to be by the genera- 

 tion of carbonic oxide and sulphurous acid, with the disengage- 



