| Water | 42 gallons |
| Cochineal | 12 pounds |
| Salts of tartar | 1 1/2 pounds |
| Potash alum | 3/4 pound |
| Nitrous acid, nitromuriate of tin | 44 pounds |
| Muriatic acid, nitromuriate of tin | 60 pounds |
| Pure block tin, nitromuriate of tin | 22 pounds |
Should give specific gravity 1.310.
Boil the water with close steam, taking care that no iron touches it; add the cochineal and boil for not more than five minutes; then turn off the steam and add salts of tartar and afterwards carefully add the alum. If it should not rise, put on steam until it does, pass through a 120-mesh sieve into a settling vat, and let it stand for 48 hours (not for precipitation). Add gradually nitromuriate of tin until the test on blotting paper (given below) shows that the separation is complete. Draw off clear water after it has settled, and filter. To test, rub a little of the paste on blotting paper, then dry on steam chest or on the hand, and if on bending it cracks, too much tin has been used.
To Test the Color to See if it is Precipitating.—Put a drop of color on white blotting paper, and if the color spreads, it is not precipitating. If there is a {278} colorless ring around the spot of color it shows that precipitation is taking place; if the white ring is too strong, too much has been used.
Black Lakes For Wall-paper Manufacture:
Bluish-Black Lake.—Boil well 220 parts of Domingo logwood in 1,000 parts of water to which 2 parts of ammonia soda have been added; to the boiling logwood add next 25 parts of green vitriol and then 3.5 parts of sodium bichromate. The precipitated logwood lake is washed out well twice and then filtered.
Black Lake AI.—Logwood extract, Sanford, 120 parts; green vitriol, 30 parts; acetic acid, 7° Bé., 10 parts; sodium bichromate, 16 parts; powdered alum, 20 parts. The logwood extract is first dissolved in boiling water and brought to 25° Bé. by the addition of cold water. Then the remaining ingredients are added in rotation, the salts in substance, finely powdered, with constant stirring. After the precipitation, wash twice and filter.
Aniline Black Lake.—In the precipitating vat filled with 200 parts of cold water enter with constant stirring in the order mentioned the following solutions kept in readiness: Forty parts of alum dissolved in 800 parts of water; 10 parts of calcined soda dissolved in 100 parts of water; 30 parts of azo black dissolved in 1,500 parts of water; 0.6 parts of “brilliant green” dissolved in 100 parts of water; 0.24 parts of new fuchsine dissolved in 60 parts of water; 65 parts of barium chloride dissolved in 1,250 parts of water. Allow to settle for 24 hours, wash the lake three times and filter it.