three Pound of the Tincture to evaporate gently, and put the rest into Glass-Bottles set round your Furnace, so that they may be heated, and ready to fill the Cucurbit as fast as the Exhalation consumes its Tincture, which may be done with a Glass Ladle, or the Bottles themselves, lest the Waters being cold might cause the Cucurbit to burst, and so all would be lost.
Reduce ten Pound of this by evaporation to two and half, or three at most, which will be a very high Tincture, pour it into two or three glazed Earthen Vessels, and place them all Night in a moist cold place, and you'll find the Vitriol at bottom, and stick∣ing to the sides of the Vessels, like little long Icicles, which will have the true colour of Oriental Eme∣ralds, pour all the remaining Waters into the Cu∣curbit, and dry the Vitriol that it may not stick, pre∣serving it in a close Vessel.
Place your Cucurbit again on the Furnace to eva∣porate anew at the consumption of half the Waters, and crystalize the strong Tincture as before. Thus whilst any Water remains evaporate and crystalize until all be consumed, to the end that none of this may be lost, whose Vertues are infinitely useful, not only in the Art of Glass, and the Metallick, but in Physick too, for the curing of many Chronick Di∣stempers, which we pass over in silence, as foreign to our Subject, and continue to prescribe the rest of this rare Work, to conceal nothing from the Curi∣ous, but give them entire satisfaction.