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. CCXL. Another Way to make Ultra-marine.

GRANTING the two former ways to be suffici∣ent, we will however here give a third, which we believe may as well be pleasing to those who are not satisfied with the other; as to such Persons as have a Curiosity for these sorts of Work; and thus we propose to proceed.

Not to discourse of the Ways to try the goodness of the Lapis Lazuli, which we have mentioned suffi∣ciently already, you must break it into gross pieces, as small as Nuts, then set these in a Crucible into the Furnace, till they redden with heat, and so cast them into cold Water; do thus six or seven times, and so reduce them to impalpable Powder in a Por∣phyry-Mortar well covered over, lest the Powder which is very subtile, should disperse away into the Air, and then searce it with a fine Searce also co∣vered.

After this, take of Rosin of Pines, ordinary black Pitch, Mastick, fresh Wax, and Turpentine, of each three Ounces, of Incense, and Linseed-Oyl, each one Ounce, melt all together in an Earthen Vessel, stirring them very well, that they may mix; this Stuff being well incorporated, cast it into Water, and keep it for use.

To each Pound of Lapis Lazuli, add ten Ounces thereof, and set them to dissolve in a Pot over a small Fire, first melting the Cement, and then cast∣ing on the Lapis Lazuli by little and little, observing such an order in this, and continually stirring the Mass with a Stick, that they may mix insensibly to∣gether;

afterwards cast the Mass into an Earthen Vessel of cold Water, and anointing your Hands with Linseed-Oyl, mould it up into a number of Cakes, or Rolls, which leave in cold Water for five Days, shifting the Water every other Day.

This done, put them into a large and very clean glazed Earthen Vessel, pouring on them some clean hot Water; when that cools, pour in more hot, and do thus till the Pastils soften with the heat of the Wa∣ter: This done, put them into hot Water, and let them be until it receive a Bluish colour; strain this Wa∣ter to reserve the grosser pieces, and so put it into another glazed Earthen Vessel very clean, adding more to the Pastils, which strain through a fine Searce afterwards among the former; continue this until all the Colour be extracted, and no more re∣main behind.

Your Water must be only warm, otherwise it will occasion a Blackness in the Colour, which is to be taken care of, and imports very much.

All your coloured Waters being in the Vessel, you may cleanse them of any Unctuosity, by reposing them for twenty four Hours, in which time the Co∣••our will stick to the bottom; then you may pour off ••he Water gently into another Vessel, and it will carry off the Grease along with it; strain it after∣wards into the Vessel where the Colour is again, through a fine Searce, and all the Grease and Nasti∣••ess will be left behind; do thus thrice, stirring the Colour very well every time you return the Water ••o it, that the Filth and Grease may ascend from it, ••nd it will always stay in straining on the Searce be∣••ind the Water.

This done, let the Colour precipitate entirely, ••nd so pour off all the Water very leisurely, for fear ••f disturbing it; dry this Colour, and you'll have ••elicate Vltra-marine.

If you would imitate this Colour at little charge, make use of our Blue-Enamel, after the same man∣ner, and instead of the Lapis Lazuli, observing with∣out exception, the like Regimen and Prescription just now delivered in every respect, and by this means you'll have a very pretty agreeable Colour to Paint with, and for tinging of Glass.

Many other Ways might be given here for making Vltra-marine, besides these we have already laid down, but because the principal part of the Prepa∣ration is in every one the same; we look upon these as sufficient, and that it would be but needless to re∣peat any more.

That the Lapis Lazuli may be made by Art as fine and good as the Natural, which is gotten from the Mines, we allow, and should freely assign the Me∣thod for it, if there were a scarcity thereof in France, but since we have of it in abundance, 'tis much better to employ the time in working the usual way, than spend it unprofitably by taking a more tedious Method.