The art of glass shewing how to make all sorts of glass, crystal and enamel : likewise the making of pearls, precious stones, china and looking-glasses : to which is added, the method of painting on glass and enameling : also how to extract the colours from minerals, metals, herbs and flowers ... : illustrated with proper sculptures / written originally in French, by Mr. H. Blancourt, and now first translated into English ; with an appendix, containing exact instructions for making glass-eyes of all colours.

CHAP. LIX. A second Species of Chalcedony.

THE second sort of Chalcedony ought to be finer than the former: The Preparations are as fol∣low.

Put into a Glass Body a Pound of Aqua fortis, and three Ounces of coppel'd Silver granulated, the bet∣ter to dissolve.

In another Glass Body put also a Pound of Aqua fortis, with five Ounces of Mercury well puri∣fied and passed through the Glove, and close it well.

Take likewise another Glass Vessel, and put into it also a Pound of Aqua fortis, with two Ounces of Sal-Armoniac to dissolve in it.

After it is dissolv'd add to it Crocus Martis prepa∣red, as in Chap. 27. Feretto of Spain, of Chap. 22. Cop∣per calcined as in Chap. 32. Leaves of Copper calcin'd by means of Sulphur, as in Chap. 31. of each half an Ounce, the whole reduced into Powder; taking care to put them in one after another, and little by little, for fear the Vessel should break.

Then put in another Earthen Body, one Pound of Aqua fortis, with two Ounces of Sal-Armoniac; and the whole being dissolv'd, add successively as before of good crude Antimony, of blue Enamel which the Painters use; of red Lead, and of Vitriol well purified of each one half Ounce; the whole well powder'd, and put in little by little, as we have said, for fear of breaking the Vessel, then close it well.

Take also another Glass Body, wherein put one Pound of Aqua fortis, and two Ounces of Sal-Armo∣niac; being dissolv'd, add to it two Ounces of pre∣pared Zaffer, as we have shewn in Chap. 17. a quar∣ter of an Ounce of Manganese of Piedmont also pre∣pared, as in Chap. 18. half an Ounce of thrice calci∣ned Copper, as in Chap. 33. with an Ounce of Cinna∣bar; the whole being well pounded, put it by little and little into the Vessel; taking care (as we have said) that the Powders don't by too much swelling break the Vessel; then close it well.

You must have a sixth Vessel of the same bigness with the rest, wherein likewise put a Pound of Aqua fortis, and two Ounces of Sal-Armoniac; as soon as it is dissolved, cast in two Ounces of Ceruse little by little, for that will cause a great fermentation. Then add the like weight of Painters red Lake, and as much of Iron Scales from the Anvil, putting it in little by little, as we have heretofore admonish'd, and for the same Reasons; and lastly proceed very

slowly in all these Operations; then stop your Ves∣sel well.

All your six Vessels being on a gentle fire of Ashes, or in a warm Bath, to hasten the Solution of your Materials, you must stir them at least six times a Day, during the twelve in which you leave them in that heat, that the Aqua fortis may the better penetrate the Powders, and they communicate their Tinctures the better to the Glass. The twelve Days being past, take a great Glass Crucible that will hold the whole, and lute it well for fear of breaking; let the lute dry, then pour in gently your Materials in the six Matras's one after the other, after ha∣ving well stirred each of them beforehand; then put your Cucurbite on a gentle Ash Fire, and fit to it a Head and Receiver, and lute well the Joints; then distil gently all the Aqua fortis for the space of Twenty four Hours, that is in the Body, making a very gentle Fire towards the end, otherwise the Powders may be spoiled by too much heat, and the Spirits which ought to remain in the Powder would pass into the Receiver. Then they will remain at the bottom of the Vessel of a yel∣lowish red colour, which keep in a Glass well stop∣ped, for tinging Glass, or Crystal, which is yet better, as I have shewn in the preceding Chap∣ter.