Take of the Tartar of white Rhenish wine made into powder, pour upon it sweet rain or running water, so that to ℔ j. of tartar there be ℔ x. or ℔ xij. of water, or so much that the tartar may be dissolved by it in the boyling, and then boyl the mixture with the water in a tinned kettle, or which is better, in a glazed pot, until it be quite dissolved, and in the mean while take off the skum (with a wooden skimmer) still as it riseth in the boyling: and when no more skum riseth, and all the tartar is dissolved, then pour the solution thus hot through a linnen cloth, tyed straight on an earthen glazed vessel, that the remaining sliminess may be separated. The tartar water being strained, let it stand for 24. or 30. hours without stirring, and there will stick a crystallized tartar to the sides of the vessel, which after the water is poured off may be taken out, and washed with cold water, and then dryed. This purified tartar keep, until I shall teach you, what further is to be done with it; and this tartar is pure enough for the above said purpose, _viz._ to reduce metals into oyl with it, as shall follow anon. It is also good taken of it self for an abstersive to make the body soluble. But if you desire to have it yet whiter and fairer and in great Crystals, you must proceed thus. You must know this that all salts, if they shall shoot into great crystals, there must be a great quantity of them, for of little there comes but little. And if you will make great and fair white crystals of tartar, which will be no better than the former, but only pleasant to the eye, then you must proceed in this manner.