BICHLOKIDE OF MERCURY.

475

solution, lime-water, or carbonate of soda; then filter, and test the clearliquid with nitrate of silver, which causes a white precipitate if anychloride be present {vide p. 105). If nitrate of silver be added to asolution of bichloride of mercury, we obtain a white precipitate of chlo-ride of silver, but mixed with calomel; and it is to avoid the productionof the latter substance that I prefer the method of testing just men-tioned.

Composition.— The composition of this salt is as follows:—

Eq. Eq. Wt. Per Cent. Turner.

Mercury. 1 .... 202 .... 7372 .... 73‘53

Chlorine. 2 .... 72 .... 26’27 .... 26‘47

Bichloride of Mercury . 1 .... 274 .... 99'99 .... lOO'OO

Purity’. —Pure bichloride should be white, dry, totally vapourized byheat, and completely soluble in water, alcohol, or ether.

Physiological Effects, {a.) On vegetables.— The effects of solu-tions of bichloride of mercury on plants have been examined by Seguin,and subsequently by Marcet and Macaire (Decandolle, Phtjs. Veg. 1332),and from their experiments it appears, that when grotving plants areimmersed in a solution of this salt, part of the poison is absorbed, achange of colour takes place in the leaves and stems, and death is pro-duced ; the effect on the irritable stamina of the Berberis vulgaris, andon the leaves of the Mimosa pudica, being the same as that produced byarsenic (p. 384). Bichloride of mercury is equally poisonous to crypto-gamic plants. Hence vegetable tissues soaked in a solution of it are nolonger adapted for the development of the Merulius lachrymans, and ofother fungi known under the name of the dry-rot. This, in fact, is theprinciple adopted by Mr. Kyan {Lond. Med. Gaz. xvi. 630) for the pre-servation of timber, and which is now practised by the Anti Dry-rotCompany.—{Vide Dr. Dickson’s Lecture on Dry-rot, 1837.)

{b.) On animals generally. —The effects of corrosive sublimate on ani-mals have been examined bv Ettmuller, Wepfer, Sproegel, Sir BenjaminBrodie {Phil. Trans, for 1812), Campbell, Lavort, Smith, Gaspard, Orfila( Toxicol. Gen), Schubarth, and Bostock. An abstract of these will befound in the works of Wibmer ( Wirk. d. Arzn. u. Gifte), and Christison{Treat, on Poisons). Dogs, cats, horses, rabbits, and frogs, are the ani-mals on which the experiments have been tried, and on which sublimatehas been found to exercise a poisonous operation, and the same kind ofeffect is presumed, from analogy, to be produced on all other animals.The results of these experiments have been so briefly yet clearly statedby Dr. Christison, that I cannot do better than quote his words:—“ Cor-rosive sublimate causes, when swallowed, corrosion of the stomach; andin whatever way it obtains entrance into the body, irritation of that organand of the rectum, inflammation of the lungs, depressed action, and per-haps also inflammation of the heart, oppression of the functions of thebrain, and inflammation of the salivary glands.” I may add, that mer-curial fetor and salivation have been observed in horses, dogs, andrabbits.

(c.) On man. —a. In small or therapeutic doses, as from one-eighth to one-fourth of a grain, it frequently exerts a beneficial effect on diseases (syphi-litic eruptions, for example), without producing any obvious alteration inthe actions of the different organs. Occasionally, especially when the