GREENS. Baryta Green.—Mix 2 parts caustic soda and 1 part chlorate of potash, and gradually add 2 parts very finely powdered manganese ; heat gradually up to dull redness, then allow to cool, powder, and exhaust with water ; filter and cool, and add a solution of nitrate of baryta to the fil trate. A violet-coloured baryta precipitate forms ; this is carefully washed, dried, and treated with I-1 part of caustic baryta, hydrated, and g,radually heated up to redness, with constant stirring. The cooled mass is powdered, and finally washed to remove any exce,ss of baryta.
Brighton Green.—Suparately dissolve 7 lb. sulphate of copper and 3 lb. sugar of ltad, each in 5 pints water ; mix tho solutions, stir in 24 lb. whiting, and when the maes ie dry, grind to powder.
Brunswick Grcen.—(a) Pour 3 parts saturated solution of sal ammoniac over 2 parts copper filings, contained in a vessel capable of being closed, and keep the mixture in a warm place for some weeks, when the newly-formed pigment is separated from the inoxidized copper hy washing on a sieve; it is then washed with water, and slowly dried in the shade. (b) A solution of crude ear bonato of ammonia is added to a mixed solution of alum and bine vitriol, as long as it affects it ; in a short time, the precipitate is collected, washed, and dried. (c) Lighter shades are produced by the addition of sulphate of baryta, or alum.
Chrome or Guignet's Green.—Fuse together 3 parts boracic acid and 1 part bichromate of potash at a dull-red heat on the hearth of a flame-furnace. This forms a borate of chromium and potash, with evolution of oxygen. The MEIN is repeatedly washed with boiling water, which causes decom position, and consequent separation of hydrated oxide of chromium and a soluble borate of potash. The oxide is washed, and ground very fine.
Emerald Green.—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 parte water, the mixture being constantly stirred until the precipitate becomes a heavy granular powder, when it is filtered through calico, and dried.
Manganese Green.—Intimately mix 3-4 parts caustic baryta moistened with water, 2 parts nitrate of baryta, and 2 parts oxide of manganese ; place in a crucible heated to dull redness, fuse, pour out, pulverize, digest in boiling water, wash in oold water, and dry in an atmosphere free from carbonic acid.
Mountain Green.—(a) Native green carbonate or bicarbonat,e of copper is ground to powder, either with or without addition of a little orpiment or chrome yellow. (b) Add a solution of car bonate of soda or potash to a hot mixed solution of alum and sulphate of copper.
Pruesian Green.—A mixture of Prussian blue and gamboge.
Sap Green.—(a) The juioe of buckthorn berries (see Drugs, p. 795) iB extracted by allowing them to ferment in wooden tubs for 7-8 days, and pressing and straining ; a little alum is added to the juice, whioli is evaporated down to a suitable consistence, and run into bladders to dry and harden. (b) Mix 11 oz. powdered arsenious acid, 11 lb. carbonate of potash, and 1 gal. boiling water ; diesolve, filter, and add to another eolution of 2 lb. crystallized eulphate of copper in 3 gal. water, producing lf lb. of pigment.
Scheele's Green.—Dissolve 1 part powdered white arsenio and 2 parte commercial potash in 35 parts boiling water ; inter, and add the solution gradually, while still warm, to a filtered solution of 2 parts sulphate of copper, ss long as a precipitate falls ; wash with warm water, and dry.
Vienna or Schweinfurth Green.—(a) Dissolve 8 lb. arsenious acid in the least possible quantity of boiling water, and add it to 9-10 lb. verdigris in water at 481° (120° F.) passed through a sieve ; set aside the mixed ingredients till the mutual reaction produces the desired shade. (b) Dissolve 50 lb. sulphate of copper and 10 lh. lime in 20 gal. good vinegar, and add tl 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.
Douglas' Green.—Barium chromate is precipitated by adding to a solution of barium chloride a sufficiency of a soluble chromate to effect complete separation ; to the lemon-yellow chromate, is added 20 per cent. of strong sulphuric' acid, which produces a deep-red by the liberation of chromic acid ; the mass is then ground, and heated to redness, when it becomes green.