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The three ingredients are now ground separately to a very fine powder. The mills which effect this, and incorporate, are so similar, that a description will be given under the head of “Incorporation.” Screening.After being ground in this way, the saltpetre is passed through a slope cylindrical reel, covered with copper sieving wire of 60 meshes to the inch, which, as it revolves, sifts it to the required fineness, being then received in a box or bin underneath. The charcoal and sulphur are likewise passed through similar reels of 32 and 60-mesh wire respectively, and that which remains without passing through, is ground again under the runners.

The Project Gutenberg EBook of Class Book for The School of Musketry Hythe, by E. C. Wilford Published 1861