)8o Natural Magick, c BooJ{ij.

as Lead foil'd upon Glass. , Plain Looking-glasses arc prepared of Crystal, and ofGlass s those of Crystal are polished by wheels, and require another Artifice. But acVenice

How Glass Looking-glasses are made,

T have seen it. They take the melted Glass out with an Iron - with their blast theyframe an empty Pillar ; they open it on one side with their tongs, and whilst it isred hot they lay it upon a plain plate of Iron, that is equally made - and they put itinto the furnace again, to make it softer; and that it may get the perfect plainness otthe iron plate, they leave it over the furnace to cool by degrees : When it is cool,they do thus

Polish slain Glasses.

They fasten it upon a plain Table with Gyp; underneath lyeth a most polite plainplate of iron ; they cast upon it the foresaid sand; they rub it with water by a stick,leaning thereon, until it be perfectly plain; they take it from the Table, and glewit on the other side, to polish them both : then they make them perspicuous, as I saidthey did. Now will I shew

To terminate slain Glass Looking-glasses,

Glass or Crystal Looking-glasses, when they are made plain aud equal, the Artistmakes a foil of the fame bigness ofTin, that is level and thin, as perfectly as he can.For if Crystal or Glass had no foil of Lead behind it, by its strength and thickness itcould never terminate cur sight, nor stay the Image Printed upon it, but it wouldlet it flip away; for Glass is pure and transparent, and so would not contain it, byreason of its brightness; and so the Image would vanish in it, as light in the Sun.Wherefore upon this foil you shall wipe over with Quicksilver, by the means of aHares scot, that it may appear all as Silver: and when you fee it fast on the superfi-cies, you shall put it upon a fair white paper, and so upon the Glass; but first madeclean with a linen clout, and polished: for if you handle it with your hands, tUefoilwill not stick to it: with your left hand press down the Glass, and with the righttake away the Paper, that the foil may cleave every where, and they bind fast toge-ther ; laying a weight upon it for some hours, and so let it stand and stir it not. NowI will shew

How a foil is put upon a Concave Glass,

But it is more laborious to lay a foil on a Concave-Glass r Prepare then a foil of thebigness of your Glass, that you shall lay upon the Convex superficies ; and holding itfast with a finger of your left hand upon the Centre , with your right hand you shallfit the foil rcund about, and shall extend it on the said superficies, until it becomeof the fame form with that convex superficies , and stick every where even unto ir.Then of moist Gyp shall you prepare a form of the Glass, namely , by pouring Gypupon the Convex superficies; and when the Gyp is dry, you have the foist). Uponthe form extend a foil of Tin, and let it agree perfectly with the foim every where,because the form and the foil are made aster the same superficies: strew quick-silverupon the foil, and as I said, make it stick by means of a Hares foot. The Artists callthis Avivaret put paper upon it, and pressing this upon the Glass, take away thepaper ; when you knew it sticks fast, take away your hand, and lay on a weight, andafter take it away, but with a careful balancing of your hand, lest it take wind, andthat the quick silver may all flick fast every where. New remains how

To terminate (sonvex-Glasfes.

Make Glass Balls, but cf pure Glass,and without bladders as much as you can, as thereceivers for distillations; and from the hollow iron that it is blown in by , let thisliquid moisture be projected , namely, cf Antimony and Lead ; but the Antimonymust be melted twice or thrice, and purged, and cast Colophcnia in. So stir themixture in the hollow vessel, and what remains cast forth: and so in Germany theymake Convex-Glasses. Chap*