3. (Douault-Wiéland.)—a. From rock crystal, 4056 gr.; minium, 6300 gr.; potash, 2154 gr.; borax, 276 gr.; arsenic, 12 gr.
b. From rock crystal, 3600 gr.; ceruse of Clichy (pure carbonate of lead), 8508 gr.; potash, 1260 gr.; borax, 360 gr.
4. (Fontanier.) Pure silica, 8 oz.; salt of tartar, 24 oz.; mix, bake, cool, treat the fused mixture with dilute nitric acid until effervescence ceases, and afterwards with water as long as the washings affect litmus paper; next dry the powder, add to it of pure carbonate of lead, 12 oz. and to every 12 oz. of the mixture add of borax, 1 oz.; triturate in a porcelain mortar, melt in a clean crucible, and pour the fused mass into cold water; dry, powder, and repeat the process a second and a third time in a clean crucible, observing to separate any revived lead. To the third frit add of nitre, 5 dr., and again melt. The product is perfectly limpid and extremely brilliant.
5. (Lançon.) Litharge, 100 gr.; pure silica, 75 gr.; white tartar or potash, 10 gr.
6. (Loysel.) Pure silica, 100 parts; red oxide of lead (minium), 150 parts; calcined potash, 30 to 35 parts; calcined borax, 10 parts; arsenious acid, 1 part. This produces a paste which has great brilliancy and refractive and dispersive powers, and also a similar specific gravity to the oriental diamond. It fuses at a moderate heat, and acquires the greatest brilliancy when remelted, and kept for 2 or 3 days in a fused state, in order to expel the superabundant alkali, and perfect the refining (‘Polytech. Journ.’). The
products of the above formulæ are not only employed to imitate the diamond, but they also form the basis of the other factitious gems. (See above.)
7. (Yellow diamond.) Strass, 500 gr.; glass of antimony, 10 gr.
Eagle Marine. From strass, 3840 gr.; copper stain, 72 gr.; pure zaffre, 1 gr.
Emerald. 1. From strass, 7000 gr.; carbonate of copper, 65 gr.; glass of antimony, 7 gr.
2. Paste, 960 gr.; glass of antimony, 42 gr.; oxide of cobalt, 31⁄2 gr.