Page:History of the Royal Society.djvu/307

 in eight hours they use to moisten the Powder with a little fair Water; others, who are more curious, put Water something thickned with quick-lime; others use White-wine Vinegar, others Aqua-vitæ: But if it be not moistned with something once in eight hours, the Powder will grow dry, and in half an hour after it will take fire. As soon as the Powder grows dry, you may find it, though at a distance, by the noise of the Mill; for then the Pestles will rebound from the bottom of the Trough and make a double stroke. The only danger to the Mill is not from the Trough; for many times the iron Gudgeons grow hot for want of greasing, and then the Dust that flies about will be apt to fire, and so the Mill blows up.

'From the Mill the Powder is brought to the Corning-house, of a middle temper between moist and dry. The way of corning it is with two hair Sieves join'd together, the upper Sieve inclosing some part of the Hoop of the lower Sieve: The upper Sieve hath holes of the size you will have the Powder grained at; the holes of the lower Sieve are much lesser: The upper Sieve they call their corning Sieve, the lower their wet Duster: They lay the Powder upon the upper Sieve some two inches thick; upon that a Piece of heavy wood made like a Trencher, of about eight inches diameter, and two and a half in thickness, called a Runner, which when the Sieve is moved, by its weight and motion, forces the Powder thorough the upper Sieve, and that corns it. Then the lower Sieve receives the Powder, and lets the dust go thorough the Bin, over which the Sieve is shaken, called the Dustingin.

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