INCORPORATING THE INGREDIENTS.
Incorporation.
The charge is spread pretty evenly over the surface of the bed, and moistened with from four to six pints of distilled water; the quantity varying according to the state of the atmosphere; the runners are then set in motion, and run from seven to eight revolutions per minute for three and a half hours, during which time the powder is often routed up by a copper-shod spud, and watered slightly with a fine rose watering pot, according to the experience of the millman; at the end of this time the mixture is thoroughly incorporated, possesses all the chemical properties of Gunpowder, and is taken off the bed in the form of a cake, varying from a quarter to half an inch in thickness, and of a blackish-grey colour. Mill cake.This is called “Mill Cake,” and when broken, the fracture should exhibit the same uniform appearance, without presenting any sparkling or yellow specks; should this, however, be the case, it is a sign of the ingredients not being sufficiently incorporated. Proof of mill cake.In this stage it undergoes certain proofs; samples of the cake are taken from every charge that is worked, dried in an oven, and granulated; half a drachm of this is fired in a vertical eprouvette, which it ought to raise 3.5 inches; and half an ounce is flashed on a glass plate. If very little residue or ash is left, it is an additional proof of its being well incorporated, and that the millman has done his work properly.
Importance of incorporation.
Incorporation is by far the most important process in the manufacture of Gunpowder; for, however carefully the other part of the fabrication is carried on, should there be a failing in this, the powder will be worth nothing.
Object of manufacture.
The great and ultimate object to be attained in the manufacture of Gunpowder is, to produce that which shall give equal results with equal charges; the greatest regularity should therefore be observed in this stage. The millman should have great experience; the runners and beds should be, as nearly as possible, the same size and weight, and driven at the same speed throughout the factory; at any rate, each charge should be worked to the same number of revolutions; the motion of the runners should also be as uniform as possible, which is very satisfactorily accomplished by each water-wheel being regulated by a governor.