Obs. The preparation of mercurial ointment according to the common plan is a process of much labour and difficulty, and usually occupies several days. The instructions in the Pharmacopœias are very meagre and unsatisfactory, and, so far as details go, are seldom precisely carried out. Employers grumble, and operatives become impatient, when they find the most assiduous trituration apparently fails to hasten the extinction of the globules. To facilitate matters, various tricks are resorted to, and various contraband additions are often clandestinely made. Among the articles referred to, sulphur and turpentine are those which have been longest known, and, perhaps, most frequently employed for the purpose; but the first spoils the colour, and the other the consistence, of the ointment; whilst both impart to it more or less of their peculiar and respective odours. On the Continent, oil of eggs was formerly very generally used for the purpose, and is even now occasionally so employed. Nearly half a century ago Mr W. Cooley clearly showed that the difficulty might be satisfactorily overcome by simply triturating the quicksilver with 1⁄8 to 1⁄4 of its weight of old mercurial ointment, before adding the lard; and that the effective power of this substance was in direct proportion to its age, or the length of time it had been exposed to the air. His plan was to employ the ‘bottom’ and ‘scraping’ of the store pots for the purpose. At a later period (1814-15) Mr Higginbottom, of Northampton, repeated this recommendation, and at length the plan has been imported into the Pharmacopœia Borussica. About twenty years since, “we reopened an investigation of the subject, which extended over several months, during which we satisfied ourselves of the accuracy of the assertion of M. Roux, that the mercury in mercurial ointment exists entirely, or nearly so, in the metallic state, and not in the form of oxide, as was generally assumed. We succeeded in preparing an excellent sample of mercurial ointment by agitating washed suet and quicksilver together in vacuo. The quantity of oxide present at any time in this ointment is variable and accidental, and is largest in that which has been long prepared; but in no case is it sufficient to materially discolour the fat after the metallic mercury is separated from it. We were led to conclude that the property alluded to, possessed by old ointment, depends solely on the peculiar degree of consistence or viscidity of the fat present in it, and on the loss of much of the thoroughly greasy, ‘anti-attritive’ character, possessed by
the latter in a recent state. In practically working out this idea we obtained pure fats (MAGNETIC ADEPS; SEVUM PRÆPARATUM), which, without any addition, were capable of reducing, in a few minutes, 8, 16, 32, and even 48 times their weight of mercury. We also found that the formula of the Pharmacopœia might be adopted, and that a perfect ointment might be readily obtained by skilful management in from half an hour to an hour, even without these resources. All that was necessary was to employ a very gentle degree of heat by either performing the operation in a warm apartment or by allowing the mortar to remain filled with warm water for a short time before using it. Suet or lard, reduced either by gentle warmth or by the addition of a little almond oil to the consistence of a thick cream, so that it will hang to the pestle without running from it, will readily extinguish 7 or 8 times its weight of running mercury by simple trituration. The exact temperature must, however, be hit upon, or the operation fails. This fact was afterwards noticed in the ‘Ann. de Chim.,’ and some other journals.” (A. J. Cooley.)
M. Pomonti has proposed a method of preparing strong mercurial ointment, which, modified to suit the English operator, is as follows:—Fresh lard, 8 parts; solution of nitre (see below), 1 part; mix by trituration, add of mercury, 32 parts, and again triturate. The globules disappear after a few turns of the pestle, but reappear in a few minutes, and then again disappear to return no more. When this happens, the trituration is to be continued for a few minutes longer, when lard, 24 parts, is to be rubbed in, and the ointment at once put into pots. It is said that the globules are so completely extinguished as to escape detection, even when the ointment is examined by a microscope of low power. The Solution.—Nitre, 100 gr.; water, 1 fl. oz.; dissolve. This quantity is sufficient for a kilogramme of mercury.
M. Lahens strongly recommends for the rapid preparation of mercurial ointment the application of oil of almonds in the following proportions:—Mercury, 1000 parts; oil of almonds, 20 parts; lard, 980 parts. The mercury is first triturated with the oil for about fifteen minutes, after which its globules are said to be no longer discernible by the naked eye; 200 parts of the melted lard are now added, and the trituration continued to the complete extinction of the metal, which is generally accomplished within an hour. The ointment is then mixed with the remainder of the lard. See Ointment of Oxide of Mercury.
Ointment, Mercurial (Milder). Milder blue ointment, Trooper’s o., Unction; Unguentum hydrargyri mitius, U. cæruleum mitius. Prep. 1. Stronger mercurial ointment, 1 lb.; lard, 2 lbs.
Dose, &c. In the itch and several other
cutaneous diseases, as a dressing to syphilitic ulcers, to destroy pediculi on the body, &c. Each drachm contains 10 gr. of mercury. That of the shops generally contains considerably less.
2. (With SOAP; Unguentum hydrargyri saponaceum; Savon mercuriel).—a. (Draper.) Mercurial ointment (softened by a gentle heat), 1 oz.; hydrate of potassa, 1 dr., dissolved in water, 1⁄2 fl. oz.; triturate them together until the mass solidifies.
b. (Swediaur.) Milder mercurial ointment, 8 parts; soft soap, 2 parts; camphor, 1 part. In periostitis, engorgements of the testicles, soft corns, &c. See Ointment of Nitrate of Mercury, &c.
Ointment, Mercurial (Compound). (B. P.) Mercurial ointment, 6; yellow wax, 3; olive oil, 3; camphor, 11⁄2. Melt the wax and oil, and when the mixture is nearly cold, add the camphor in powder and the mercurial ointment, and mix.