Chap. XLI. Of Liniments, 8$c.
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part of the axunge obviates, in a great measure, this inconve-nience. The hardening is entirely owing to the excess ofthe acid in the solution of mercury. Hence the London col-lege have acted in 1809 very inconsiderately in increasingthe quantity of nitrous acid, from two ounces by weight totwo fluidounces, which caused, as Mr Phillips found, violentaction, and the evolution of much noxious vapour, when thesolution of mercury is mixed with the axunge, and rendersthe ointment extremely corrosive. They have in 1815 cor-rected this error : But the property which nitrate of raercury,prepared by ebullition, has, of being decomposed by wa-er, furnished me with an easy way of getting rid of all ex-cess of acid, and of procuring the'subnitrate of mercury inthe state of the most minute division possible. An ointment,prepared with this subnitrate, had a most beautiful goldencolour; after six months was perfectly soft; and had all theproperties desired.
When the citrine ointment is too hard, it should be soften-ed by triturating it with lard or oil; for, if melted with them,it very soon harden^ again.
Medical use. —This ointment has the very best effects inherpes, tinea capitis, and similar obstinate cutaneous affec-tions, and is almost specific in psorophthalmia, in those slightexcoriations of the tarsi, attended with extreme itching, andin all the inflammations of the eyes, attended by eruptive dis-orders of the hairy scalp or face. It is most conveniently andeffectually used, by rubbing a piece of the size of half a gar-den pea, with the point of a hair pencil, over the tarsi, amongthe roots of the ciliae, and allowing a small quantity to get onthe inner membrane of the palpebrse. In obstinate cases, aweak solution of muriate of mercury, used as a collyrium a-long with this ointment, proves a most powerful remedy.
Unguentum subacetitis cupki. Ed.Ointment qfSubacetite of Copper.Take of
Resinous ointment, fifteen parts ;Subacetite of copper, one part.
Unguentum aeruginis. Dub.Ointment of Verdigris.Take of
Ointment of white resin, one pound;Prepared verdegris, half an ounce.Make into an ointment.
B