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. LX. The third and last way of Chalcedony.

THIS third way surpasses the other two in Beau∣ty; it is something tedious, but the Learned know that what is most perfect, requires most time.

To make this Preparation, you must use the Aqua fortis of Chap. 52. putting one Pound in a Glass Ma∣trass, with four Ounces of Leaf-Silver to dissolve, and stop the Matras.

Take another Matras, wherein put a Pound of the same Aqua fortis, with five Ounces of Mercury pu∣rified with Salt and Vinegar after this manner. Take common Salt, sprinkle it with Vinegar in a Wooden-dish, where add to it a little common fair Water to make it dissolve, put in your Mercury, and stir it well with a Wooden-Pestle to draw out the Blackness; repeat washing them often with fresh Salt and Vinegar, till there be no more Blackness; then dry them with warm Linen or Cotton, and pass it thro' the Glove, then it will be purified, and fit to put in your Aqua fortis. When it is dissolved, stop the Matras and keep it.

Take another Glass Body, wherein put a Pound of Aqua fortis with three Ounces of fine Silver calci∣ned. Amalgamate the Silver with the Mercury, as the Goldsmiths usually do, and put it into a Crucible, with its weight of common Salt purified, as we have heretofore shewn: Then put the Crucible on hot Coals, that the Mercury may evaporate, and that only the Silver remain at bottom, which will be pu∣rified and calcined. Then add to that calcined Sil∣ver,

an equal weight of common Salt purified as be∣fore, mix them well together, and put them over the Fire in a Crucible to calcine them afresh; then wash them well with warm Water to take out the Salt; then put this Silver into a Glass Vial fill'd with common Water, which boil till one fourth part be consumed, then let it cool and settle to the bottom, then decant off the Water, and put more upon it: Reiterate this Process with fresh Water three times, and at the fourth dry the Silver, and put it into your Aqua fortis, and stir it well, and stop the Ma∣tras.

We have promised to give the way of purifying common Salt, which is this. Take what quantity you will of Sea-Salt, dissolve it in a convenient quantity of common Water, boiling it for the space of two Hours, then let the Water rest, that the earthy part of the Salt may settle to the bottom: Then filter the Water, and evaporate it in an Ear∣then Vessel, or rather in a Glass Cucurbit, till the Salt remain dry at the bottom. Dissolve this Salt again, making the Water boil, then let it stand for the Dregs to settle, after which filter it and evapo∣rate it as before; which you must continue to do, till it leave no more Faeces or Dregs, and it will be well purified and prepared.

To continue our Preparation of the Materials, you must put into a Glass Matras a Pound of Aqua fortis, with three Ounces of purified Sal-Armoniac; that is to say, filter'd and whitened till it leave no Faeces or Dregs, as we have shewn in common Salt: Then dissolve in that Water a quarter of an Ounce of Sil∣ver, and stop the Vessel well.

Take another Glass Matras, and put into it also a Pound of Aqua fortis, with two Ounces of Sal-Ar∣moniac; being dissolv'd, put into that Water, of Cinnabar, of Crocus Martis calcined with Sulphur as

above; of Vltramarine, and of Ferretto of Spain, prepared as in Chap. 22. of each half an Ounce, the whole well pounded into Powder; you must do this little by little as we have heretofore hinted for fear of breaking the Vessel, by the fermentation which they make with the Aqua fortis; then stop the Ma∣tras.

Put into another Matras a Pound of Aqua fortis, and dissolve in it two Ounces of Sal-Armoniac as be∣fore; add to it of Crocus Martis calcined, as in Chap. 25, with calcined Tin, known among the Glass-Men, of Zaffer described in Chap. 17. and of Cinnabar, of each half an Ounce, the whole well powder'd, and cast little by little into your Matras, for the Reasons before assigned, which require that great precaution; then stop the Matras.

Take another Glass Body, wherein put one Pound of Aqua fortis, and dissolve in it two Ounces of Sal-Armoniac; then add one Ounce of small Leaves of Copper calcined, as in Chap. 31, half an Ounce of Scales of Copper thrice calcined, as describ'd in Chap. 34, half an Ounce of Manganese of Piedmont prepared, as in Chap. 18, and half an Ounce of Scales of Iron which fall from the Smiths Anvil, the whole well pounded, which cast little by little into your Matras for fear of breaking it, then stop it well.

Put into another Glass Body one Pound of Aqua fortis, and two Ounces of Sal-Armoniac: The disso∣lution being made, put to it little by little half an Ounce of red Lead, one Ounce of Scales of Copper of Chap. 34, half an Ounce of crude Antimony, and as much Caput Mortuum of Vitriol purified, the whole well pulveriz'd; then stop the Ma∣tras.

Take another Glass Matras, put into it one Pound of Aqua fortis with two Ounces of Sal-Armoniac; add to that Water of Orpiment, of white Arsnick, of Painters Lake, half an Ounce of each; the whole being well powder'd, and put into a Matras with the same precaution as before, stop it well.

We have not repeated at each Operation, that you must put your Matras on an Ash Furnace over a gen∣tle heat, or in a warm Bath to hasten the Solution of the Materials; because we have told you it must be al∣ways done in Chap. 58, in speaking of the Preparation of those things which serve to tinge the first Species of Chalcedony; which may suffice for the instruction of those who employ themselves in this Art. We will add, that all the nine Matrasses mentioned in this Chapter, must remain fifteen Days in the same heat, stirring them often every Day, that the Water may the better operate on the Materials subtilizing them, and well opening their Tinctures. Then put all these Materials, with the Aqua fortis, into a great Glass Body, little by little, that they may unite well to∣gether. Close the Body and set it in the same heat, stirring it well for six Days. After that, take a great Glass Cucurbit well luted half way up the Body of it, put it on an Ash Furnace, put into it all the Mate∣rials out of your Body, fit to it a Head and Receiver, lute well all the Joints, then distil it during the space of twenty four Hours, over a very gentle Fire, for fear the Colours should be spoil'd, that the Water pass gently over, and the Spirits remain in the Pow∣der, which of green will become yellow.

Thus putting that Powder in the requisite Dose (as we have taught in the first Species of Chalcedony) into purified Glass Metal, made of broken pieces of Cry∣stal, and not of Fritt; and adding to it in its due time, calcined Tartar, Soot of Chimney, Crocus

Martis made with Vinegar, observing all we have on this Subject remarked, these Materials will give an opacity to Glass, which may be worked twenty four Hours afterwards, managing it well with pro∣per Tools, and often heating it; and you'll have things made of an extraordinary Beauty, greater then can be imagin'd.

The End of the Second BOOK.