2720. To Make Purple of Cassius

2720.    To Make Purple of Cassius. This is a verifiable pigment, which, stains glass and porcelain a beautiful red or purple hue. Its preparation is one of great nicety, and is liable to fail even in the most experienced hands. Mix together separate solutions of 1 part crystallized protochloride of tin, and 2 parts crystallized perchloride of tin; this mixture, added to a solution of 1 part crystallized chloride of gold, makes a beautiful purple colored precipitate, which should immediately be washed, filtered, and dried. An excess of the protochloride produces a blue, yellow, or greenish tinge; the perchloride in excess gives a red or violet cast.

2721. French Purple of Cassius

2721.     French Purple of Cassius. This is similar in preparation to the last receipt, but differs in one ingredient employed, substituting perchloride of iron for the perchloride of tin. This purple keeps in the air unaltered for a long time.

2722. Purple of Cassius

2722.    Purple of Cassius. To a moderately dilute solution of sesquichloride of iron, add a solution of protochloride of tin, until the mixture becomes green, and dilute the mixture with an equal bulk of water. Next prepare a solution of terchloride of gold, as neutral as possible, in the proportion of 1 part gold in 360 parts water; then add the tin solution, with constant stirring, as long as any precipitate is produced. Wash the precipitate as quickly as possible by decantation, and dry at a gentle heat.

2723. Buisson's Preparation of Purple of Cassius

2723.    Buisson's Preparation of Purple of Cassius. Two solutions of tin are required. The first consists of a neutral solution of 1 part tin in nitric acid. The second is made by dissolving 2 parts tin in a mixture of 1 part hydrochloric acid with 3 part3 nitric acid; a little heat may be cautiously applied towards the end of this process, to prevent any protoxide of tin from remaining in the solution.

Next dissolve 7 parts gold in an aqua-regia composed of 6 parts hydrochloric acid and 1 part nitric acid; and mix the solution at once with 3500 parts water; then add the whole of the second tin solution, subsequently adding by degrees the first tin solution, ceasing the moment the right color is obtained. Too little will produce a violet color; too much, a brown. Wash the precipitate very quickly, and dry. When dry it appears brown.

2724. Improved Vehicles for Colors

2724.     Improved Vehicles for Colors. One measure of saturated solution of borax, with 4 of linseed oil. The pigment may be ground with the oil or the mixture. Or, a solution of shellac with borax, as in making Coathupe's ink. (See No. 2484 (Shellac Ink, or Coathupe's Writing Fluid).)

2725. Improved Vehicles for Water Colors

2725.     Improved Vehicles for Water Colors. Water colors, mixed with gelatine, and afterwards fixed by washing with a solution of alum, or; curd of milk, washed and pressed, then dried on fine net, and when required for use, mixed with water and the coloring matter.