2431. Opal

2431.     Opal. Take 1 ounce paste, 10 grains horn silver, 2 grains calcined magnetic ore, 26 grains calcined bones. Or: 10 pounds paste, and 1/2 pound calcined bones.

2432. Ruby

2432.    Ruby. Take 40 parts paste, and 1 part oxide of manganese. Or: 1 part topaz paste that has turned out opaque, and 8 parts strass; fuse for 30 hours, cool, and fuse small pieces before a blow-pipe. Or: 8 ounces strass, 84 grains each precipitate of cassius (see Nos. 2720 (To Make Purple of Cassius) to 2723), peroxide of iron, golden sul-phuret of antimony, and manganese calcined with nitre; add 1 ounce or more of rock crystal. Or: 1 pound paste and 3 drachms purple of cassius. Or: 4 ounces paste, 4 ounces glass of antimony, and 3/4 drachm purple of cassius; this turns on the orange.

2433. Sapphire

2433.    Sapphire. Fuse 1152 parts paste and 68 parts oxide of cobalt for 30 hours in a luted Hessian crucible. Or: 8 ounces paste and 49 grains oxide of cobalt. A little manganese may be added to this last receipt.

2434. Topaz

2434.     Topaz. Melt 96 grains paste and 1 grain calcined peroxide of iron. Or: 1008 grains paste, 43 grains glass of antimony, and 1 grain purple of cassius. (See Nos. 2720 (To Make Purple of Cassius) to 2723.)

2435. Turquois

2435.    Turquois. Take 10 pounds blue paste, 1/2 pound calcined bones.

2436. Yellow Diamond

2436.    Yellow Diamond. Take 1 ounce strass, and 10 grains glass of antimony. Or: 1 ounce strass and 24 grains chloride of silver.

2437. Chrysolite

2437.     Chrysolite. Strass, 5 pounds; calcined peroxide of iron, 3 to 4 drachms.

2438. Eagle Marine

2438.    Eagle Marine. Paste of strass, 10 pounds; copper highly calcined with sulphur (copper-stain), 3 ounces; zaffre, 1 scruple.

2439. Emerald

2439.    Emerald. Lancon's paste (see No. 2426 (Lancon's Paste or Strass)), 9612 grains; acetate of copper, 72 grains; peroxide of iron, l1/2 grains. Or: Dou-ault - Wi'eland paste (see No. 2425 (Doualt-Wi'eland's Paste or Strass)), 4608 grains; green oxide of copper, 42 grains; oxide of chrome, 2 grains. Or: Paste, 1 ounce; glass of antimony, 20 grains; oxide of cobalt, 3 grains. Or: Paste, 15 ounces; carbonate of copper, 1 drachm; glass of antimony, 6 grains.

2440. Lapis Lazuli

2440.    Lapis Lazuli. Paste, 10 pounds; calcined horn or bones, 12 ounces; oxides of cobalt and manganese, of each, 1/2 ounce; mix. The golden veins are produced by painting them on with a mixture of gold powder, borax, and gum water, and gently heating till the borax fluxes.

2441. Amethyst

2441.    Amethyst. Take 500 grains paste, 3 grains oxide of manganese, and 2 grains oxide of cobalt. Or: 4608 grains paste, 36 grains oxide of manganese, 24 grains oxide of cobalt, and 1 grain purple of cassuis. (See Nos. 2720 (To Make Purple of Cassius) to 2723.) Or: 9216 grains paste, 15 to 24 grains oxide of manganese, and 1 grain oxide of cobalt.

2442. Aqua Marina, or Beryl

2442.    Aqua Marina, or Beryl. Take 3200 grains paste, 20 grains glass of antimony, and 1 grain oxide of cobalt. Or: 2304 grains paste, 16 grains glass of antimony, and 1 grain oxide of cobalt.

2443. Aventurine, or Gold Stone

2443. Aventurine, or Gold Stone. Fuse 10 grains scales of iron, 50 grains paste, and 5 grains protoxide of copper, until the copper is reduced to metallic form, then allow the mass to cool very slowly, so that the minute crystals of metal become equally diffused through it. By substituting oxide of chromium for the protoxide of copper, the stone appears brown, filled with minute gold spangles; or by using a less quantity of the chromium, a greenish gray stone, filled with green spangles, is produced.

2444. Parisian Diamonds

2444.      Parisian Diamonds. These beautiful imitations of the gem are merely fused oxide of tin. It is a pity that their brilliancy is not permanent, as they become quite dull in time.

2445. Boettger's Artificial Rubies

2445.      Boettger's Artificial Rubies. Moisten recently precipitated and well washed hydrate of alumina, with a few drops of neutral chromate of potassa, and kneaded so that the mass assumes a scarcely perceptible tinge; then roll it out into small sticks, about the thickness of a finger, and dry them slowly, filling up any cracks that may occur in drying with fresh hydrate of alumina. When perfectly dry, warm a stick a little, and bring a portion into the end of the flame of a compound (oxyhydrogen) blow-pipe. In a few minutes several minute balls form, of such intense hardness as to scratch quartz, glass, and granite. These, however, when cut and polished, appear slightly opaque.

2446. Boettger's Artificial Emerald

2446.    Boettger's Artificial Emerald. This is made in the same manner as his rubies, by employing nitrate of nickel instead of the chromate of potassa. The same plan, substituting oxide of chromium for chromate of potassa, will produce gems of considerable hardness and beauty, though slightly opaque; which may, however, be lessened by the addition of a very little silica.