Dr. Pereira's Elements of materia medica and therapeutics : abridged and adapted for the use of medical and pharmaceutical practitioners and students and comprising all the medicines of the British Pharmacopœia, with such others as are frequently ordered in prescriptions or required by the physician / edited by Robert Bentley and Theophilus Redwood ; with an appendix.

  • Jonathan Pereira
Date:
1874
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Licence: Public Domain Mark

Credit: Dr. Pereira's Elements of materia medica and therapeutics : abridged and adapted for the use of medical and pharmaceutical practitioners and students and comprising all the medicines of the British Pharmacopœia, with such others as are frequently ordered in prescriptions or required by the physician / edited by Robert Bentley and Theophilus Redwood ; with an appendix. Source: Wellcome Collection.

    1118/1180 (page 1086)
    [1086] Dissolve the perchloride of mercury in four pints of distilled water, aiding the solution by the application of heat, and add this to the solution of soda. Stir them together ; allow the yellow precipitate to subside; remove the supernatant liquor by decanta- tion; thoroughly wash the precipitated oxide on a calico filter with distilled water; and finally dry it by the heat of a water-bath. Characters and Tests.—A yellow powder readily dissolved by hydrochloric acid, yielding a solution which, with solution of am- monia, gives a white precipitate. It is entirely volatilised when heated to incipient redness, being resolved into oxygen gas and the vapour of mercury.] Precipitated oxide of mercury (mercuric oxide), being in a finely divided amorphous condition, is more easily acted upon by chemical agents than the red oxide previously ordered and still retained in the Pharmacopoeia; and on this account it is used in making the oleates of mercury introduced by Mr. Marshall, and is preferred by some medical men as a topical application. The only precaution required to be observed in the process by which this oxide is directed to be prepared, is that the caustic soda should be kept well in excess of the mercuric salt; and, with the view of maintaining this condition throughout the precipitation, the solution of chloride of mercury is to be added to the alkali, instead of mixing them in the reverse order. The decomposition is represented by the following equation:—HgCl2 + 2NaHO=HgO-f 2NaCl + H20. The precipitated oxide will have a bright yellow colour, which it will retain after having been washed and dried by the heat of a water-bath. It is identical in composition with the red oxide. If long exposed to the influence of light it loses its clear yellow colour, and acquires a greyish colour, which appears to be due to partial reduction. Therapeutics.—The yellow and red oxides of mercury are not often administered internally ; but, if they should be, the same pre- caution ought to be observed with regard to the dose as is required in the case of corrosive sublimate, which they resemble in activity. The yellow oxide is used externally like the red oxide, for which see page 346. [§ Injeotio Morphiae Hypodermica. Hypodermic Injection of Morphia. A solution of acetate of morphia containing one grain of the acetate in twelve minims of the injection. Take of Hydrochlorate of Morphia . . . 88 grains. Solution of Ammonia Acetic Acid . . - of each a sufficiency. Distilled Water