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. CCXXXVI. The Method of cleansing the Ultra-marine when 'tis se∣parated from the Cement.

AFTER you have extracted all your Colours out of the Cement, and the Water quite setled and separated from them, pour on some of the mild Lixivium before prescribed, and so wash them with your Hands (but don't rub it between them) thus you'll take away all the Grease of the Cement; af∣terwards wash it three or four times in fair Water, and let the Waters settle well before you put them into their proper Vessels.

You may else another way purge the Vltra-marine, thus. Take the Yolks of Pullets-Eggs, that have been fed only with Corn, and not with Greens, prick these with a Pin, and so moisten the Colours, knead∣ing the Mass with your Hands, and washing it after∣wards with your mild Lixivium, until the Lixivium falls off clear again. This done, wash them three or four times over with fair Water, letting the Wa∣ters settle well before you put them into their Ves∣sels.

This last way of purifying the Vltra-marine, is mighty effectual; but here is another help to be u∣sed with it, which is a very great Secret, and per∣formed thus: After the Colours are quite washed ac∣cording to former direction, as well as possible, you must cast therein by little and little, a Bull's-Gall, rubbing it by degrees with your Hands; so wash them often in clear Water, and you'll have the Co∣lour in full perfection.