RED LAV′ENDER. See Tincture of Lavender (Compound).
RED LIQ′UOR. The crude solution of acetate or sulpho-acetate of alumina employed in calico printing. It is generally prepared by mixing crude sulphate of alumina with about an equal weight of crude pyrolignite of lime, both being in the state of solution.
RED PIG′MENTS. The preparation of the principal red pigments are described under their respective names. The following list includes most of the reds in use:—
Arme′nian Bole. Syn. Bole Armenian; Bolus Armeniæ, L. Formerly imported from Armenia, Portugal, Tuscany, &c.; now generally made by grinding together a mixture of whiting, red oxide of iron, and red ochre, in nearly equal proportions.
Red, Brown. A factitious mixture of red oxide of iron and red ochre, in variable proportions.
Car′mine.
Carmina′ted Lake.
Red Chrome. Syn. Dichromate of lead, Red chromate of l.; Plumbi dichromas, P. chromus rubrum, L. Prep. 1. Boil pure carbonate of lead with chromate of potassa, in excess, until it assumes a proper colour; then wash it well with pure water, and dry it in the shade.
2. Boil neutral chromate of lead with a little water of ammonia or lime water.
3. (Liebig and Wöhler.) Fuse saltpetre at a low red heat in a Hessian crucible, and throw in chromate of lead (pure chrome yellow), by small portions at a time, as long as a strong ebullition follows upon each addition of the pigment, observing to stir the mixture frequently with a glass rod; after repose for a minute or two, pour off the fluid part, and, as soon as the solid residuum is cold, wash it with water, and dry it by a gentle heat.