1200 lbs. silex, 800 " red lead, 440 " pearlash, 50 " nitre, 10 " phosphate of lime, 10 oz. white oxide of antimony, 24 " manganese, 32 " arsenic, 20 " borax. GERMAN SHEET GLASS. 400 lbs. silex, 130 " soda, 126 " hydrate of lime, 4 " charcoal, 7 " nitrate of soda, 4 " arsenic, 1 " manganese. Gold-colored spangles may be diffused through the glass by mixing gold-colored talcs in the batch. AGATE. To 150 lbs. flint batch add 10 " phosphate of lime, 6 " arsenic. BLACK. 600 lbs. flint batch, 40 " manganese, 46 " oxide of iron. LIGHT EMERALD GREEN. 200 lbs. flint batch, 2-1/2 " iron filings, calcined, 1/2 " antimony. ORIENTAL GREEN. 110 lbs. flint batch, 1 " oxide of uranium, 2 oz. carbonate of copper. OPAL. 500 lbs. batch, 60 " phosphate of lime, 4 " arsenic, 20 " nitrate of soda. Said to turn without cooling. William Gillender, of England, gives the following receipt for Bohemian Red, or Ruby:-- Sand, 62 lbs. Lead, 76 " Nitre, 22 " Antimony, 8 oz. Manganese, 3 " Add one ounce of purple of Crassus to every eighty pounds of the above batch. WAX RED. To 15 lbs. flint batch add 1 " raw brass, 3/4 " crocus martus. This he says is very good. TURQUOISE. To 1100 lbs. flint batch add 90 " phosphate of lime, 15 " arsenic, 15 " calcined brass dust. VIOLET. To 100 lbs. flint batch add 1 " calcined brass, 1-1/2 " zaffre. Receipts for window-glass are as numerous as for flint. The following are in general use in England, so says Gillender:-- CROWN GLASS. Sand, 1400 lbs. Quick lime, 480 " Sulphate of soda, 560 " Charcoal, 25 " PLATE GLASS. Sand, 300 lbs. Sulphate of soda, 450 " Quick lime, 100 " Nitre, 25 " Charcoal, 5 " DIAMOND GLASS. Four pounds of borax, one pound of fine sand; reduce both to a subtile powder, and melt them together in a closed crucible set in an air furnace, under a strong fire, till fusion is perfect. Let it cool in the crucible, and a pure, hard glass, capable of cutting common glass like a diamond, which it rivals in brilliancy, is produced. LEAD. Lead is an important and costly ingredient of flint-glass, used as a protoxide, either as litharge or red lead, and should be perfectly pure, for the presence of any other substance or metal will be shown in the color of the glass. Consequently, the purity of the glass depends mainly on the quality of the metallic lead and its being well manufactured.