Green, Schweinfurt

This splendid green pigment is the ace to-arsenite of copper. Prep. 1. Acetate of copper and arsenious acid, equal parts, are each di olved separately in the least po ible quantity of boiling water, and the solutions mixed whilst still as hot as po ible; an olive-green precipitate falls, which, by being boiled in the liquor 5 or 6 minutes, changes to a dense granular powder of a superb green colour. 2. Instead of boiling the solution containing the precipitate, it is allowed to cool and stand for several hours, or until the powder a umes a granular and beautiful tint. Very rich. 3. (Kastner.) Arsenious acid, 8 lbs., is di olved in water as before, and added to verdigris, 9 or 10 lbs., diffused through water q. s., at 120° Fahr., the pap of the other being first pa ed through a sieve; the mixed ingredients are then set aside till the mutual reaction produces the proper shade. 4. (Dr Ure.) Sulphate of copper, 50 lbs., and lime, 10 lbs., are di olved in good vinegar, 20 galls., and a boiling hot solution of white arsenic, 50 lbs., is conveyed as quickly as po ible into the liquor; the mixture is stirred several times, and then allowed to subside, after which it is collected on a filter, dried and powdered. The supernatant liquor is employed the next time for di olving the arsenic. 5. See Green, Emerald ( above ). Obs. This is a very fine, permanent green pigment. “A great deal of needle alarm has been excited about its supposed deleterious effects. It is extensively employed for staining wall-papers, and persons inhabiting rooms thus papered are said to have had their health seriously deranged by the arsenical fumes evolved from it. Now, it is utterly impo ible that arsenic could volatilise from such a compound at ordinary temperatures; it does not decompose at any temperature below redne .” (Watts.) [It is, however, probable that the air of such apartments is sometimes charged with the poisonous pigment through its becoming mechanically detached from the paper. To breathe an atmosphere so impregnated would be dangerous. The use of papers coloured with Scheele’s green, especially of the kind called ‘flock,’ should, therefore, be carefully avoided.— Ed. ]