COPPEK.

495

doubtless acquainted with it, though he seems to have confounded itwith sulphate of iron. His chalcanthum cyprium was, perhaps, sulphateof copper. This salt has had various synonymes, such as blue vitriol(•vitriolum cmruleum) Roman vitriol, blue copperas, blue stone, bisulphateof copper.

Natural History. —It occurs in copper mines (as those of Cornwall ,&c ) and is formed from sulphuret of copper by the joint agency of airand water. The cupreous solutions of copper mines are termed watersof cementation.

Preparation. —It may be prepared by evaporating the w r ater foundin, or issuing from, copper mines. It is also produced by roasting copperpyrites, lixiviating the residuum to dissolve the sulphate, and evaporatingso as to obtain crystals. In this process both the sulphur and the copperof the pyrites abstract oxygen from the air, and become, the one sulphuricacid, the other oxide of copper: these by their union constitute thesulphate of copper.

Properties. —This salt occurs in fine blue crystals, whose primaryform is the doubly oblique prism. Its sp. gr. is 2 2. It has a stypticmetallic taste, and reacts on litmus as an acid. By exposure to theair it effloresces slightly, and becomes covered with a greenish whitepowder. When heated it loses its water of crystallization, and becomesa white powder (pulvis sympatheticus.) By a very intense heat it isdecomposed,—sulphurous acid and oxygen are evolved, and oxide ofcopper left. It dissolves in about 4 parts of water at 60°, and 2 parts ofboiling water. It is insoluble in alcohol.

Characteristics. —Its characteristics are those of the sulphates(vide p. 265), and of the cupreous compounds (vide p. 493.)

Composition. —Its composition is as follows:—

Eq. Eq.Wt. Per Cent. Thomson. Berzelius .Oxide of Copper .... 1 . 40 ... 32 ... 32 . . 32*13

Sulphuric Acid. 1 . 40 ... 32 ... 32 . . 31*57

Water. 5 . 45 ... 36 ... 36 . . 36*30

Crystallized Sulphate of Copper 1 . 125 . . . 100 . . . 100 . . 100*00

Impurity. —The commercial sulphate of copper sometimes containstraces of sulphate of iron. It may be detected by excess of ammonia,which throw's down the oxide of iron, but dissolves the oxide of copper.

Physiological Effects, (a.) On vegetables .—It is poisonous to plants(Decandolle, Phys. Veg. 1335) : hence its use in preventing dry rot(Merulius lachrymans), by soaking timber in it, according to Mr.Margary’s patent; and in destroying or preventing the smut (Uredosegetum), or bunt (U. caries), in com, by immersing the grain in a weaksolution of it: the solution is not made sufficiently strong to injure the seed.

(b.) On animals .—This salt operates as a poison to animals. Sixgrains killed a dog in half an hour, without producing any appearanceof inflammation (Drouard). Applied to a wound it destroyed the animalin twenty-two hours, and the body was every where in a healthy state(Duncan, in Christison on Poisons, 432). Orfila [Tor. Gen.) also foundthat it proved fatal in a few hours when applied to w'ounds. The onlysymptoms mentioned are dulncss, loss of appetite, and sometimespurging. Inflammation of the mucous membrane of the stomach and(rectum was found after death.