Page:History of the Royal Society.djvu/296

 'When this is done, turn out the useless insipid Earth out of the Tubs, which you must fill with new Earth, and continue this Operation, till you have in the same manner lixiviated all the Earth: Then fill your Copper with your Liquor, which Copper, for one of the Profession, must be about two hundred weight, and set strongly in a Furnace of brick-work; besides, on one side of your Furnace you are to place a Tub full of your Liquor, which at a Tap below may dribble as fast into the Copper, as the force of the Fire doth waste your Liquor, which Invention is only to save charges in Fewel. When you have boyled it up to that height, that a little of it flirted off the finger on a live Charcoal, will flash like Gun-powder (which for the most part falls out to be about two Days and a Nights boiling) at what time, upon tryal, a hundred weight of the Liquor contains about five and thirty pound weight of Peter. But the Workmen seldom make use of any further indication, than by finding the Liquor hang like Oyl on the sides of the brasen Scummer, when 'tis dipped into it, which is a sign it is fit to be passed through the Ashes, which is done in this manner.

'You must prepare two Tubs, fitted after the manner of the first, where you put your Earth, saving that at the bottom of these Tubs, you must lay Reeds or Straw a foot high; over them place loose boards, pretty near one another; over them, a little more Straw (which is to keep the Ashes from the top, and to give the Liquor room to drein the better from them:) Then fill up your Tubs with any sort of Wood-ashes to half a foot of the top; then pour on the foresaid Liquor, as it comes Rh