482
ELEMENTS OF MATERIA MEDICA.
and changes its colour. Heated with potash, it yields iodide of potas-sium and reguline mercury.
Composition. —It consists of
Eq. Eq.Wt. Per Cent.
Iodide of Mercury ... 1 . 328 . 99*99
Physiological Effects. —It is a powerfully irritant poison. A scruplekilled a rabbit within twenty-four hours, and a drachm destroyed apointer-dog in five days (Cogswell, Essay onlodine and its Compounds, 160).
In small but repeated doses, it appears to exercise a specific influenceover the lymphatic and glandular system. Two grains taken dailycaused salivation in two instances (Biett, Lancette Frangaise, Juin 1831).
Uses. —It has been used in syphilis and scrofula, especially when theyoccur in the same individual. Lugol ( Essays on the Effects of Iodine inScrofulous Disorders, by Dr. O’Shaughnessy, p. 170) employed an oint-ment of it in those forms of external scrofulous disease which resemblesyphilis. Ilicord ( Lancette Franc. 1834, No. 65) gave it internally withgood effect in syphilis infantum. Biett (O’Shaughnessy’s Transl. ofLugol’s Essays, p. 201) has successfully employed it in syphilitic ulcera-tion and venereal eruptions.
Administration. —The dose of it for adults is from one grain graduallyincreased to three or four. Ilicord gave from one-sixth to one-half of agrain to children of six months old. Biett employed it internally, andalso externally, in the form of ointment, to the extent of twelve or four-teen grains daily, by the way of friction.
Pilulje Hydrargyri Iodidi, Ph . Lond. (iodide of mercury, 3j.;confection of dog-rose, 5iij.; ginger, powdered, 3j. M.)—Five grains of
these pills contain one grain of the iodide. The dose, therefore, will befrom five grains to a scruple.
Unguentum Hydrargyri Iodidi, Ph . Lond. (iodide of mercury,3j.; white wax, 3ij.; lard, 3vj. M.)—This is used as a dressing forscrofulous ulcers, or for syphilitic ulcers in scrofulous subjects. It is alsoemployed in tubercular skin diseases, as lupus, rosacea, and sycosis.(Rayer, Treat, on Skin Diseases.)
Hydrar'gyri Biniddidum. — Bini'odide of Mer'cury.
Preparation. —There are two methods of preparing this compound.The process given in the London Pharmacopoeia is as follows:—Anounce of mercury and ten drachms of iodine are to be rubbed together,alcohol being gradually added until the globules are no longer visible.The powder is to be dried with a gentle heat, and kept in a well-stoppedvessel. The alcohol facilitates the combination of iodine and mercury, asin the process for making the protiodide.
Biniodide of mercury may also be prepared by adding a solution ofbichloride of mercury to one of iodide of potassium so long as any precipi-tate takes place. 274 grains of bichloride will be required to decompose332 grains of iodide of potassium: these proportions are about 8 of thefirst to 10 of the second. In this process double decomposition takesplace : biniodide of mercury precipitates, while chloride of potassiumremains in solution. If excess of iodide of potassium be employed, it