GUNPOWDER. 203 



" After this intimate mixing, it is conveyed away in 

 the shape of mill-cake, and firmly pressed between 

 plates of copper, and the mass is more compressed 

 and in thinner cakes. 



" It is then broken into small pieces with wooden 

 mallets, and taken to the corning-house, where it is 

 granulated by putting it into sieves, the bottoms of 

 which are made of bullock's hide, prepared like parch- 

 ment, and perforated with holes about two tenths of 

 an inch in diameter. From twenty to thirty of these 

 sieves are secured to a large frame, moving on an 

 eccentric axis, or crank, of six inches' throw ; two 

 pieces of lignum vitce, six inches in diameter, and two 

 inches or more in thickness, are placed on the broken 

 press-cakes in each sieve. The machinery is then put 

 in rapid motion ; the balls of lignutn vitce pressing 

 upon the powder, and striking against the sides of the 

 sieve, force it through the apertures in grains of vari- 

 ous sizes on to the floor, from whence it is removed 

 and again sifted through finer sieves of wire, to sep- 

 arate the dust and classify the grain. 



" The grains afterwards undergo a process of glaz- 

 ing by friction against each other, in barrels containing 

 nearly two hundred pounds, making forty revolutions 

 per minute, and lasting several hours, according to the 

 fancy of the purchaser. This part of the business I 

 entirely disagree with, as injurious to quick and certain 

 ignition. 



" It is finally dried by an artificial temperature of 

 140 Fahrenheit ; which is suffered gradually to 

 decline. 



