190 GUNPOWDER. 



der marked FF in the shops, and placing it on a piece of polished 

 copper, I heated the copper over the flame of a candle ; the 

 gunpowder soon sent forth a strong sulphureous vapour, and 

 when it had been dried so long that no more fume or smell could 

 be distinguished, the residue weighed nineteen grains, the loss 

 amounted to five grains. The remainder did not explode by a 

 spark like gunpowder, but like a mixture of saltpetre and char- 

 coal, and it really was nothing else, all the sulphur having been 

 dissipated. Gunpowder was formerly dried by being exposed to 

 the heat of the sun ; and this method still obtains in France, and 

 in some other countries : afterwards a way was invented of ex- 

 posing it to a heat equal to that of boiling water ; at present it 

 is most generally in England dried in stoves heated by great iron 

 pots ; with any tolerable degree of caution, no danger of ex- 

 plosion need be apprehended from this method. All the watery 

 part of the gunpowder may be evaporated by a degree of heat 

 greatly less than that in which gunpowder explodes, that degree 

 of heat having been ascertained by some late experiments to be 

 about the six hundredth degree on Fahrenheit's scale, in which 

 the heat of boiling water is fixed at two hundred and twelve. 

 There is more danger of evaporating a part of the sulphur in 

 this mode of drying gunpowder than when it is dried by exposure 

 to the sun. 



" The necessity of freeing gunpowder from all its moisture is 

 obvious from the following experiment, which was made some 

 years ago before the Royal Society. A quantity of gunpowder 

 was taken out of a barrel and dried with a heat equal to that in 

 which water boils, a piece of ordnance was charged with a cer- 

 tain weight of this dried powder, and the distance to which it 

 threw a ball was marked. The same piece was charged with an 

 equal weight of the same kind of powder, taken out of the same 

 barrel, but not dried, and it threw an equal ball only to one half 

 the distance. This effect of moisture is so sensible, that some 



