Of counterfeiting precious Stones I yp

lour of chalk, it must be taken out; and when it i$ cold, grinde it, and lay it in wa-ter in some wide-mouth'd vessel a quarter of a day. When the water is grown clear,filtrate ic, and strain it into another vessel, and then pour water again unco thesettlement, observing the same things we spoke before, until the water have takenout all the salt, which will come to pass in the third or forth time. Pour your wa-ters which you saved, into a vessel of glass; and all things being ready, put live colesunder it, and attend the work until the water be consumed by the force of the fire*

• which being done, the salt will stick to the bottom: it being thus made, preserveit in a dry place, lest it turn to oyl.

Chap. IT.

How Flinty or Crystal it to be prepared , and how Pastils are boiled,

T He matter of which Gems are made, is either Crystal or Flint, from whence westrike fire, of round pebbles found by river sides: those are the best which aretaken up by the river Thames, white, clear, and of the bigness of an egge; for ofthose are made best counterfeit Gemms, though all will serve in some sort. Semethink that Crystal is the best for this purpose , because of the brightness and transpa-rency of it; but they are deceived. The way of making Gems, is this: Take river-pebbles and put them into a fornacc, in that place where the retorted flame is mostintense; when they are red hot, take them out and fling them into water : thendry them, and powder them in a mortar, or a hand-mill, until they are very fine ;put them into a wide-moutbed vessel, full of rain water, and shake it well in yourhands, for so the finest part will rise to the top, and the grossest will settle to thebottom: to that which swims at top pour fresh water, and stir the dust again: anddo this oftentimes, until the gross part be quite separated and sunk down. Thentake out the water, and let it settle, and in the bottom there will lie a certain slimymatter; gather together, and reserve the refined powder. But whil’st the stone isground, both the morter and the mill will lose somewhat of themselves, whichbeing mixt with the powder will foul the Gem: wherefore it wist be worth the la-bor to wash that away: to which end, let water be often poured into the la el, andstirred about; the dust of the moner will rise to the top,by reason of its levity , andthe powder of the pebbles will retire .to the bottom by reason of its weight; skimthe lavel, and separate them with a spoon , till all that sandy and black dust be takenoff. then strain out the water, and reserve the powder dry. These being done, wemust teacn

How Pastils are boiled.

Artificers call those pellets which are made of the salts, and the forenamed powderand water, Pastils. Take five parts of fait of Tartar, as many of fair of Soda; dou-ble the quantity of these of the forefpoken powder of pebbles, and mix them verywell in a stone morter: sprinkle them with water & wet them,so that they may growinto a past, and make Pastils of them in bigness of your fist j set them in the fun, anddry them well. Then put them into a fornace of reverberation, the space of sixhours, encreasing the fire by degrees, that at last they may become red hot, but notmelt; wherefore use no bellows: when they arc baked enough, let them cool, andthey will become sobard, that they will endure almost the hammer.

Chap. III.

Of the Fornaetyand the Parts thereof.

N Ow the Fornace i? to be built, which is like to that of glass-makers, but lessaccording to the proportion of the work. Let your fornace be eight foot high,aud consist of two vaults; the roof of the lower must be a handful and a half thick: thevault itself must have a little door, by which you may cast ia wood to feed the fire