186 GUNPOWDER. 



that this opinion in favour of coal from light wood is ill founded : 

 he affirms, that powder made from lime tree coal, or even from 

 the coal of the pith of the alder tree, is in no respect preferable 

 to that made from coal of the hardest woods, such as guiacum 

 and oak. This remark, if confirmed by future experience, may 

 be of service ; as it is not always in the power of gunpowder 

 makers to procure a sufficient quantity of the coal of soft wood. 

 " The mixture of the materials of which gunpowder is made 

 should be as intimate and uniform as possible ; for in whatever 

 manner the explosion may be accounted for, it is certain that 

 the three ingredients are necessary to produce it. In order to 

 procure this accurate mixture, the ingredients are previously re- 

 duced into coarse powders, and afterwards ground and pounded 

 together, till the powder becomes exceedingly fine ; and when 

 that is done the gunpowder is made. But as gunpowder, in the 

 state of an impalpable dust, would be inconvenient in its use, it 

 has been customary to reduce it into grains, by forcing it, when 

 moistened with water, through sieves of various sizes. 



" The necessity of a complete mixture of the materials, in 

 order to have good gunpowder, is sensibly felt, when such as 

 has been dried, after being accidentally wetted, is used. There 

 may be the same weight of the powder after drying that there 

 was before it was wetted ; but its strength is greatly diminished, on 

 account of the mixture of the ingredients being less perfect. 

 This diminution of strength proceeds from the water having 

 dissolved a portion of the saltpetre (the other two ingredients not 

 bein^ soluble in water) ; for upon drying the powder, the dis- 

 solved saltpetre will be crystallized in particles much larger than 

 those were which entered into the composition of the gunpow- 

 der, and thus the mixture will be less intimate and uniform than 

 it was before the wetting. This wetting of gunpowder is often 

 occasioned by the mere moisture of the atmosphere. Great 

 complaints were made concerning the badness of the gunpowder 



