COURSING, ETC, 217 



gulated by exact weight, otherwise he cannot, 

 even in this experiment, arrive at any cer- 

 tainty, in comparing the different strength of 

 powders, or of the same powder at different 

 times. Powder ought to be kept very dry, 

 as every degree of moisture injures it: good 

 gunpowder however does not readily imbibe 

 moisture ; and perhaps there is no greater 

 proof of the bad quality of powder, than its 

 growing damp quickly when exposed to the 

 air; this readiness to become moist, depends 

 on the saltpetre used in the composition not 

 having been freed from the common salt it 

 contained in its crude state, and which in 

 consequence has a very strong attraction for 

 watery particles : powder may acquire a 

 small degree of dampness, and be freed from 

 it again by drying, without much injury to its 

 quality ; but if the moisture is considerable, 

 the saltpetre is dissolved, and the intimate 

 mixture of the ingredients thereby entirely de- 

 stroyed. Drying powder with too great a 

 heat also injures it ; for there is a degree of 

 heat, which although not sufficient to fire the 



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