464

ELEMENTS OF MATERIA MEDICA.

effects of mercury. In the case mentioned by Jacob, death resulted fromthe application of it to a wart on the face.

Frederic Hoffmann, Ploucquet, Girtanner (Wibmer, op. cit.), and morerecently Mr. Brett {Lond. Med. Gaz. xiii. 117), have related instances ofpoisoning by its internal employment.

Uses. —Internally it has been administered in the form of pill invenereal diseases, but the practice is highly objectionable.

As an external agent it is used in the form of powder (obtained bylevigation) or ointment; the latter is officinal. As a caustic, it issprinkled over spongy excrescences, venereal warts, chancres, indolentfungous ulcers, &c. Mixed with eight parts of finely-powdered whitesugar, it is blown into the eye with a quill in opacity of the cornea(Mackenzie, On Diseases of the Eye, 2d ed. p. 584).

Unguentum Hydrargyri Nitrico-Oxydum, Ph . Lond. andDub. (Finely-powdered nitric-oxide of mercury, Sj.; white wax, Sij.;lard, Svj. Mix. The unguentum oxidi hydrargyri rubri, Ph . Ed. con-sists of nitric oxide of mercury, one part; lard, six parts. Mix.)—Thisointment undergoes decomposition by keeping ; its colour changing fromred to grey, in consequence of the partial deoxidation of the nitric-oxideof mercury. Dr. Duncan ( Edinb. Dispens.) says the presence of resinquickly causes it to become black. It is a valuable stimulant, and isfrequently applied to indolent sores and ulcers, when we require to in-crease the quantity and improve the quality of the discharge ; to inflamedeye-lids ( ophthalmia tarsi); chronic conjunctivitis, &c.

Hydrar'gyri Chlo'ridum. — Ohio'ride of Mer'cury.

History. —Beguin in 1608, and Oswald Croll in 1609, are the firstEuropeans who mention this compound. Mr. Hatchett (Brande’sManual of Pharmacy, 2d edit. 328) says it had been long known to thenatives of Thibet . Its discoverer is unknown. It has had a greatvariety of names. The. term calomel { calomelas, from koXoq, good,and fXac, black) was first applied to it by Sir Theodore de Mayenne(who died in 1655), in consequence, as some say, of his having had afavourite black servant who prepared it; or according to others, be-cause it was a good remedy for the black bile. Drago mitigatus, aquilaalba, manna metallorum, and panchymagogum minerale, are some of theappellations for it. Mercurius dulcis, hydrargyrum muriaticum mite,submuriate of mercury, and subchloride, protochloride, or dichloride ofmercury, are some of the more modern synonyms of it.

Natural History. — Native calomel or corneous mercury occurs incrusts, and also crystallized in four-sided prisms terminated by pyra-mids. It is found at Deux-Ponts, Carniola, and in Spain .

Preparation, (a.) By sublimation. —Chloride of mercury is preparedby sublimation from a mixture of sulphate of mercury and chloride ofsodium.

In the London Pharmacopoeia, two pounds of mercury are directed tobe boiled with three pounds of sulphuric acid, to dryness, by whichbipersulphate of mercury is obtained. When cold, this is mixed, first withtwo pounds of mercury, then with a pound and a half of chloride ofsodium, and afterwards sublimed. The sublimate is to be washed withboiling distilled water, and dried.