Stir 30 lbs. of hydrate of alumina into six quarts of acetic acid, warm, filter, and reduce to the specific gravity required.
The hydrate of alumina is prepared by dissolving 72 lbs. of alum in 100 gals. of water, and 62 lbs. soda in 100 gals. of water. The two solutions are mixed, this precipitate is washed eight times by decantation, collected on a filter and pressed. It must be dissolved on the filter before it gets dry.
Nitrate Of Alumina.
2 lbs. nitrate of lead; 2 lbs. alum; 2 quarts water.
Dissolve and filter off the liquid from the precipitate, and dilute to proper standard.
The reds are turned more yellow by nitrate than by acetate of alumina, and when the former is used more acetate of lime is taken in addition.
Acetate of Lime.
A solution of acetate of lime at 25° Tw. contains 25 per cent. of acetate of lime; generally 1⁄10th of the weight of alizarin paste is required; but with a fresh quantity of alizarin it is safer to ascertain, on a small scale, the amount needed.
Brown.
131⁄4 lbs. alizarin paste (15 per cent.); 9 quarts thickening; 2 lbs. nitrate of alumina, at 29° Tw.; 15 oz. acetate of alumina, at 19° Tw.; 15 oz. red prussiate potash, dissolved in water; 1 lb. 1 oz. acetate of lime, at 29° Tw.