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. XCI. Shewing the Way to prepare Natural Crystal, and to make a very fine Salt of Tartar, and several sorts of Pasts, for Emerald, Topaz, Chrysolite, Iacinth, Granat, Sap∣phire, Beryl or Egmarine, Carbuncles, Rubies, and se∣veral other Colours, of so great Beauty that they sur∣pass the Natural Stones themselves in every thing but Hardness.

WITHOUT doubt it will seem surprizing to several, that Art should be capable of imitating the Natural Colour of Precious Stones in so great Perfection, as that the Beauty of the Artificial should surpass that of the Natural Ori∣ental

ones, in every thing excepting their hardness, which they have been many ages in acquiring: and I doubt not but several Ingenious Men are this day searching after means to give them that too. The Curious will find in this Book all that is necessary to attain this Art, nay, and to do something more than I mention. For since Art can easy imitate Na∣ture, it is not to be doubted but that Ingenious Men may some time or other arrive to give the same per∣fection to Crystals that precious Stones have acquired in the Bowels of the Earth.

The Natural, or Rock Crystal, which we make use of, as the Basis of our Artificial Gems, is the only Stone that does not proceed from any Metal, being the first substratum of others, only made of a congealed Water, with a subtil Earth, as other precious Stones. Its Virtue proceeds from Mercury, and the Spirit of Raphael, having also a great Sym∣pathy with Saturn and Iupiter, whence it is proper for healing several Diseases. All the diversities of Gems proceed only from a sulphur or an unctuous Substance, which insinuates its self in their Compo∣sition, which fixes them more or less and also tinges them. This Sulphur is an Exhalation of Metalline and Mineral Spirits, forced up by the Central Fire, which virtually contains divers Colours, and which are determin'd and brought into act by proper Subjects.

Thus Granat and other precious Stones agree with Crystal, as Mercury does with Saturn, their harmony in the Heavens assures us of these reasons and proportions here on Earth.

Precious Stones derive their Origin from the Stars and the Primum Mobile, as do the Metals both per∣fect and imperfect, of the colour of Sulphur, and the qualities whereof they partake, and wherein they agree with the Stars. Great and wonderful

Operations might be performed with these Precious Stones, if they were separated from the Impurity of their terra damnata, and reduc'd by the universal Men∣struum into their first principles. It is only by this Menstruum, or mundane Spirit, that Metals and Mi∣nerals can also be so dissolv'd, that being full of their Attractive Virtues.

We can boldly assert that this universal Spirit con∣tains in it self all the secrets of Alchymy; and that without it, it is impossible to have the Tincture, Wa∣ter, and Salt of Precious Stones, or to make use of the admirable Virtues God has imparted to them. Yet I don't dispute but that there is a certain Acid Water Extracted from a Simple, wherein a dissolu∣tion of Gems may be made, and an admirable Ma∣gisterium, and a Precious Treasure for the Health, being prepar'd secundum Artem. That Water will also extract the Tincture of Gold, the Virtue of which is not less for preservation of Life, and curing several Malignant Fevers.

As to Artificial Gems, which are the Subject of this Book; all the Art consists in rightly imitating the Tinctures of those that are fine, which must be extracted from Subjects that resist the Fire. The Tinctures we give them are fixed in the Crystals though volatile, without altering their Colour. As for example Verdigrease being put on the Fire, becomes of another Colour, but being in fusion with the Crystal it fixes and changes not its Colour; for natural Colours always return to their principle, and the great quantity of fixed, always retains some of the volatile. You must therefore for this end take permanent Colours which change not, being mixed one with another. For example Blue and Yellow make Green, you must therefore take a Blue that cannot be altered by the Yellow you mix with it; and a Yellow that cannot be altered by the Blue▪ and so of others.

Isaac Hollandus, who has writ much on the Art of making Gems, shews us a very fine way, by which he has performed things almost incredible. We will give you some of his Preparations, among those we de••••gn to treat of, and add several curious Matters to wha•• he has said of them, both for Pasts, Tinctures, and t•• Fabrick of Gems, to Encourage the Lo∣vers of this Art to set their Hands to work at it. It is true the way is troublesome and tedious, but any one that will diligently apply himself to it, will find himself sufficiently rewarded for his pains, both by the Pleasure of seeing so fine Productions, and the Profit he may get by a thing of so small charge.