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. CCXXXVII. To strain off the Ultra-marine already Washt and Purified.

IT is necessary to strain off the Vltra-marine, and the rest of the Colours, that if any Grease, or Unctuosity of the Cement remain, it may be taken quite away, for these Colours require a Perfect and Extraordinary Purifica∣tion.

For this Purpose, take a fine Searce, and pour thereon the last Waters, with which you washed the Vltra-marine, and so strain them afterwards through another fine Searce, and a third time through Red Quintain, or Crape; but you must ob∣serve when you strain them, to let them stand till you perceive them limpid and clear, and so soak off the Water dextrously with a Spunge, and be sure not to strain them promiscuously all toge∣ther.

This being done to all the Waters, let your Co∣lours settle in their proper Vessels, and dry in the Shade; when dry, put them into little Leather∣Bags; tie these close, rubbing and pressing them with your Hands; this will make them very sub∣tile, and when the Bags are opened, they'll shew much fairer than before.