Page:History of the Royal Society.djvu/305

 The Brimstone is sifted thorough Tiffany in a Bolting mill, such as the Bakers use for Wheat-flour: the Coal is sifted thorough Lockram, in a bag made like a shirt sleeve; for the convenience of the Work-man it is done in a close Bin, with only two holes for him to put his arms in, and shake the bag about. Whatsoever of each material is not small enough to sift thorough, is brought again to the Mill to be new ground.

'As for the Peter, that must in the Copper be dissolved in as much water as will just take it up, and then the water must be boiled away till the Peter comes to the thickness of hasty-pudding. The reason of this operation is because when the Peter is thus soft, the other materials will the easilier incorporate with it, and in the next place it will not wear the wooden pestles so much when it comes to the Mill, as when it is hard and dry.

'When the Materials are in this readiness, they are weighed (only the Peter is weighed before it is put to dissolve in the Copper) and by proportion are carried to the mingling Trough, which is made of boards, like a great Chest without a cover, being about eight foot long, four broad, and three foot high. The Coal is laid in first, the Brimstone next, and the Peter at top of all; then two men with shovels stir and mingle them together for an hour, and then 'tis ready for the Mill.

'The Powder-mills are seldom made to move with any thing but water: The great water-wheel is made like that of an ordinary water-wheel, either over-shot or under-shot, according to the quantity of water they have: To the Axis of this wheel, a little way within the Mill is fastened a Rh