Page:History of the Royal Society.djvu/297

 ing hot out of the Copper, on the Ashes contained in the first Tub; then after a while draw it off at the top; and so continue putting on and drawing off, first at one Tub of Ashes, then at the other, till your Liquor grow clear, and lose the thick turbid colour it had when it went on.

'When all the Liquor hath in this manner past through the Ashes of both Tubs, that by this means all its greasy oyl is left behind in the Ashes, you must keep it for the second boyling in a Vessel by it self: in the mean time pour upon your Ashes a sufficient quantity of common Water, very hot, once or twice, to bring away what is remaining of the Liquor in the Ashes.

'When you begin the second boyling, put first into the Copper the Water that went last through your Ashes, and as that wasteth, let your strong Liquor drop into the Copper, out of the Tub above described, standing on the side of the Furnace, till the Liquor in the Copper be ready to shoot or chrystalise.

'Note, That toward the end of your boyling, there will arise great store of Scum and Froth; which must be carefully taken off with a great brass Scummer, made like a Ladle, full of little holes, and usually about that time it lets fall some common Salt to the bottom, which you must take up with the said Scummer, and lay it aside for another use.

'To know when the Liquor is ready to shoot into Peter, you need but drop a little of it on a knife, or any other cold thing that hath a smooth superficies, and if it coagulate, like a drop of tallow, and do not fall off the knife when it is turned downward, which also may be judged by its hanging like Rh