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Chap. XLI.

Of Liniments, §c.

655

Unguentum oxidi hydrargyri cinerei. Ed.Ointment of Grey Oxide of Quicksilver. «Take of

Grey oxide of quicksilver, one part;Hogs lard, three parts.

These ointments are principally employed, not with a viewto their topical action, but with the intention of introducingmercury in ail active state into the circulating system, whichmay be effected by gentle friction on the sound skin of anypart, particularly on the inside of the thighs or leo-s. Forthis purpose, these simple ointments are much better suitedthan the more compounded ones, with turpentine and the like,formerly employed ; for, by any acrid substance, topical in-flammation is apt to be excited, preventing further frictionand giving much uneasiness. To avoid this, it is necessary,even with the mildest and weakest ointment, to change occa-sionally the place at which the friction is performed.

It is requisite that the ointments in which the mercury isextinguished by trituration should be prepared with very <*reatcare; for upon the degree of triture which has been employ-ed, the activity of the mercury very much depends The ad-dition of the mutton-suet, now adopted by London and Edin-burgh, is an advantage to the ointment, as it prevents it fromrunning into the state of oil, which the hogs lard alone, inwarm weather, or in a warm chamber, is sometimes apt to doand which is followed by a separation of its constituent parts.We are even inclined to think, that the proportion of suetdirected by the London college, is too small for this purposeand, indeed, seems to be principally intended for the more-effectual triture of the mercury ; but it is much more to be re-gretted, that in a medicine of such activity, the colleges shouldnot have directed the same proportion of mercury to the fattymatter.

B

EmpLASTRCIM HYnRARGYRI. Ed.

Plaster of Quicksilver.

Take ofOlive oil,

Pine resin, each one part;Quicksilver, three parts ;Plaster of semi-vitrified oxide of lead, six parts.

Melt the oil and resin together, and when this mixture is cold,let the quicksilver be rubbed with it till the globules disap-pear ; then add, by degrees, the litharge plaster, melted,and let the whole be accurately mixed.

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