Volume 1

The elements of materia medica and therapeutics / by Jonathan Pereira.

  • Jonathan Pereira
Date:
1849-1853
Catalogue details

Licence: Public Domain Mark

Credit: The elements of materia medica and therapeutics / by Jonathan Pereira. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    907/934 (page 877)
    The importance of a sufficient quantity of acid has been already pointed out. In the process of the London College, by which, when it is strictly followed, a very fine product is obtained, acid of a sp. gr. of 1*5 is directed to be used. But the sp. gr. of commercial nitric acid rarely exceeds P38 or 1'4. Hence, therefore, a larger quantity of commercial acid is required to be equivalent to the quantity of strong acid ordered by the Pharmacopoeia. Mr. Schacht has shown that ointment spoiled by age or accident, and which has become hard, discoloured, pulverulent, or even blackened, may be restored to its original beauty by heating it with nitric acid; and he has further shown that the use of an excess of nitric acid in the manufacture of the ointment is no disadvantage, for, if the heat be continued long enough, it distils off. Stirring assists the evolution of gas, and is usually believed to favour the formation of a fine product; but Mr. Alsop asserts that a long-continued stirring is not required. When fresh prepared, this ointment has a fine golden yellow colour, a butyraceous consistence, and a peculiar nitrous odour. It is very apt to become grey when mixed with other ointments, in consequence of their deoxidizing powers; and to prevent this, an additional quantity of nitric acid should be added. It should be spread with wooden or ivory spatulas. When fresh prepared this compound contains the following substances, besides the ordinary constituents of lard and olive oil:—elaidine, red oil, elaidate of mercury (mercurial soap), and nitrate of mercury. Elaidine is a white saponifiable fat, fusible at 97° F. [S9'6 F. according to Meyer],1 very soluble in ether, but requiring 200 times its weight of boding alcohol to dissolve it. It consists of elaidic acid and glycerin. It is an irritant and slight caustic. When it has undergone decomposition by keeping, it irritates ulcers exceedingly, and even excites slight erysipelatous inflammation. We employ it as a stimulant and alterative in chronic diseases of the skin, more particularly those affecting the hairy scalp, as the different forms of porrigo, in which it is exceedingly efficacious. It is also used as a dressing to ulcers—to stimulate and cleanse them—as in foul syphilitic sores and phagedenic ulcers. Lastly, it is employed in ophthalmic diseases—more particularly ophthalmia tarsi, or psorophthalmia, in which it is applied (mixed with its own weight of almond oil) by means of a camelVhair pencil to the lids, frequently with such advantage that some have regarded it as a specific in this complaint. 173. HYDRARGYRI ACETAS.-ACETATE OP MERCURY. Formula Hg20,A. Equivalent Weight 259. History.—This compound was known to Lefebure in the 17th century. Preparation.—In the Dullin Pharmacopoeia the directions for procur- ing it are the following:— Take of Purified Mercury, Acetate of Potasb, of each, nine parts; Diluted Nitric Acid, 1 Pharmaceutisches Central-Blattfur 1840, S. 790.