Form a paste with 1 part verdigris in sufficient boiling water, pass it through a sieve to remove lumps, and gradually add it to a boiling solution of 1 part arsenious acid in 10 water, the mixture being constantly stirred until the precipitate becomes a heavy granular powder, when it is filtered through calico, and dried.
Intimately mix 3 to 4 parts caustic baryta moistened with water, 2 baryta nitrate, and 2 manganese oxide; place in a crucible heated to dull redness, fuse, pour out, pulverize, digest in boiling water, wash in cold water, and dry in an atmosphere free from carbonic acid.
Mitis-green is an .arseniate of copper, prepared by dissolving 20 parts potassium arseniate in 100 hot water, and mixing this solution with another of 20 parts copper sulphate. During the whole operation the mixture is stirred. A pulverulent precipitate of light-green or grass-green colour is formed, and is washed and dried. By varying the proportions, several tones and hues are produced; in the commercial article, these are generally due to Introduction of foreign substances. The potassium arseniate is prepared by boiling arsenious acid in concentrated nitric acid, filtering, saturating with potassium carbonate, and crystallizing the arseniate.
(a) Native green carbonate or copper bicarbonate is ground to powder either with or without addition of a little orpiment or chrome-yellow. (6) Add a solution of carbonate of soda or potash to a hot mixed solution of alum and copper sulphate.
A mixture of Prussian blue and gamboge.
-(a) The juice of buckthorn berries is extracted by allowing them to ferment in wooden tubs for 7 or 8 days, and pressing and straining; a little alum is added to the juice, which is evaporated down to a suitable consistence, and run into bladders to dry and harden, (b) Buckthorn berries, not entirely ripe, are boiled with a little water in a clean copper kettle, and upon a moderate charcoal fire. The mass is continually stirred, until it has become a kind of magma, which is pressed through cloths. The residue is washed and pressed again. The liquors are left to settle, and filtered through flannel bags, before being evaporated to the consistency of a thick extract upon a gentle fire. The thickened juice is weighed without pouring it out from the kettle (the weight of which is known); to every lb. of liquor is added 7 dr. alum dissolved in water, and the mixture is thoroughly stirred all the while. The evaporation is completed upon a water or steam bath, and continued as long as practicable without altering the colour.
The product is poured into calf-bladders, and dried in the air. (Hager.)
Dissolve 1 part powdered white arsenic and 2 commercial potash in 35 boiling water; filter, and add the solution gradually, while still warm, to a filtered solution of 2 copper sulphate as long as a precipitate falls; wash with warm water, and dry.
(a) Dissolve 8 lb. arsenious acid in the least possible quantity of boiling water, and add it to 9 to 10 lb. verdigris in water at 120° F. (48 1/2° C), passed through a sieve; set aside the mixed ingredients till the mutual reaction produces the desired shade. (6) Dissolve 50 lb. copper sulphate and 10 lb. lime in 20 gal. good vinegar, and add a boiling-hot solution of 50 lb. white arsenic as quickly as possible; stir several times, allow to subside, collect on filter, dry, and powder. The supernatant liquid is employed to dissolve the arsenic for the next lot.
Zinc oxide, 5 lb.; cobalt sulphate, 1 lb. Mix with sufficient water to form a paste, and heat to redness; a deep green pigment results. With 10 parts zinc oxide, and 1 part cobalt sulphate, a grass-green powder is obtained; and with 20 parts zinc oxide a light grass-green pigment is produced, capable of being used instead of arsenic-green. This green is permanent in contact with lime (as in mortar, &c), and has thus an advantage over green made from mixtures of chrome - yellow and Prussian blue. (Eisner.)
(a) Digest 1 lb. ground Brazil-wood in 4 gal. water for 24 hours, boil 1/2 hour, and add 1 1/4 lb. alum dissolved in a little water; mix, decant, strain; add 1/2 lb. tin solution, again mix well and filter; to the clear liquid cautiously add a solution of soda carbonate while a precipitate forms, avoiding excess; collect, wash, and dry. The shade will vary according as the precipitate is collected. (6) Add washed and recently-precipitated alumina to a strong filtered decoction of Brazil-wood.
(a) The cochineal residue left in making carmine is boiled with repeated portions of water till exhausted; the liquor is mixed with that decanted off the carmine, and at once filtered; some recently-precipitated alumina is added, and the whole is gently heated and well agitated for a short time; as soon as the alumina has absorbed enough colour, the mixture is allowed to settle, the clear portion is decanted, and the lake is collected on a filter, washed, and dried. The decanted liquor, if still coloured, is treated with fresh alumina till exhausted, and thus a lake of second quality is obtained. (6) To the coloured liquor obtained from the carmine and cochineal as just stated, a solution of alum is added, the filtered liquor is precipitated with a solution of potash carbonate, and the lake is collected and treated as before. The colour is brightened by addition of tin solution.
Boil 1 lb. cochineal and 4 dr. potash carbonate in 7 1/2 gal. water • for J hour. Remove from the fire, stir in 8 dr. powdered alum, and allow to settle for 20 to 30 minutes. Pour the liquid into another vessel, and mix in a strained solution of 4 dr. isinglass in 1 pint water; when a skin has formed upon the surface, remove from the fire, stir rapidly, and allow to settle for 1/2 hour, when the deposited carmine is carefully collected, drained, and dried.