SUBACETATE OF COPl'ER.

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Each pill contains half a grain of annnoniaret of copper. The dose isfrom one to live or six pills.

Liquor Cupri Ammonio-sulphatis, Ph . Lond. Cupri ammo-niati aqua, Ph . Dub. (Ammoniated copper, 5j.; distilled water, Sxx.Dissolve and strain. In the Dublin Pharmacopoeia one part of the saltis used to a hundred parts of distilled water).—It is applied to indolentulcers as a stimulant and detergent; and, when diluted, to the eye, toremove slight specks of the cornea.

Cu'pri Subace'tas. — Subac'etate of Copper .

History.- —Hippocrates employed verdigris, which lie terms yaXicou ibs,or rust of copper, in diseases of the eyes, and as an astringent in haemor-rhoids (Ed. lues. 035, (i3(i & 894). Theophrastus ( De Lapidibus), Diosco-rides (lib. v. cap. xci.), and Pliny {Hist. Nat. xxxiv.) describe the methodof procuring it. The Homans called it arugo. It is frequently termeddiacetate of copper ; hut this name is objectionable, since verdigris fre-quently occurs as a subsesquiacetate mixed with the trisacetate. I preferthe less precise, though more accurate term, subacetate of copper.

Preparation. —At Montpellier it is thus made:—The refuse of grapesis allowed to ferment with sour wine, and is then laid in alternate stratawith plates of copper : acetous fermentation takes place, and the metalbecomes oxidized by the combined influence of the air and acid. Inabout fifteen days the plates are covered with the acetate of copper; theyare then wetted, and exposed for a month to the air: the acetate absorbsthe water, and uniting with more oxide of copper, forms a subacctate,which is scraped off, and packed in leathern sacks for exportation. AtGrenoble verdigris is obtained by sprinkling plates of copper with ready-made vinegar (Dumas, Traite de Chim. v. 109). In this country it isprepared by exposing thin plates of copper to the action of acetic acid,or its fumes: the method now practised consists in alternating plates ofcopper with pieces of woollen cloth steeped in acetic acid; they gra-dually become corroded, and superficially covered with verdigris, whichis from time to time removed, and the operation repeated, as long as theplate lasts (Braude’s Manual of Chemistry). French verdigris is importedin sacks, weighing from 25 to 30 pounds.

Properties. —It occurs in masses or in powder. One variety is of apale bluish green colour; another is blue. Its taste is astringent andmetallic; its odour is somewhat similar to, though more disagreeable,than acetic acid. It is insoluble in alcohol. Water resolves it into asoluble acetate and an insoluble trisacetate. Hence the cupri subacetaspreeparatum of the Dublin Pharmacopoeia, and which is directed to beprepared by levigation and elutriation, is in fact the trisacetate, theverdigris having undergone a chemical change by the action of water.

Characteristics. —When digested with strong sulphuric acid, itevolves acetic acid, which is readily distinguished by its odour. Heatedin a glass tube it gives out acetic acid; the residue contains metalliccopper. If verdigris be boiled in distilled water a solution is obtained,which is known to contain copper by its colour, and by the before-men-tioned tests for the cupreous compounds (vide p. 493).

Composition. —The blue verdigris is a hydrated diacetate of copper.