A manual of pharmacy / By William Thomas Brande.

  • Brande, William Thomas, 1788-1866.
Date:
1833
Catalogue details

Licence: Public Domain Mark

Credit: A manual of pharmacy / By William Thomas Brande. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    aqueous solution has a peculiarly nauseous, acrid, and astrin- gent taste, which, when once experienced, will scarcely be forgotten; it reddens some vegetable blues, such, for instance as litmus ; but it renders the blue of violets and of some other flowers, green. It dissolves in the alkalies, and forms com- pounds with the metallic oxides generally; hence the term, 'arsenious acid applied to it. When exposed with charcoal, to heat under pressure, or when combined with potassa and heated with charcoal, as in the case of fusing it in a glass tube with black flux, it is decomposed, and a brilliant steel- grey sublimate of metallic arsenic is obtained. Arsenious acid or white arsenic consists of one proportional of arsenic combined with one and a half of oxygen, or Arsenic 38 76 Oxygen .... 12 24 50 100 If nitric acid be repeatedly distilled off white arsenic, it acquires an additional proportion of oxygen, and is converted into arsenic acid, a substance very soluble in water, very sour, and saturating the alkalies and metallic oxides, so as to pro- duce distinct neutral salts, some of which, especially the bin- arseniate of potassa, have been proposed for medical use ; but the arsenite of potassa (liquor arsenicalis) is equally effectual, and we should studiously avoid multiplying these pernicious compounds. Arsenic acid is virulently poisonous. It con- sists of one proportional of arsenic and two and a half of oxygen, or Arsenic .... 38 65 • 5 Oxygen ... 20 34-5 58 100 There now remain for discussion three important points in the pharmaceutical history of white arsenic, namely—the chemical means of detecting its presence by tests or re-agents ; the symptoms which it produces when taken in mischievous quantity; and the method of treatment which such cases require. 1 have already remarked that arsenic, even in very minute quantity, is not difficult of discovery. The suspected sub- stance should be boiled in as small a portion of distilled water as convenient, the solution filtered, and a portion of it put into three test tubes, a, 6, and c. To a add a drop or two of solution of potassa, and then a similar quantity of solu- tion of sulphate of copper; an apple-green precipitate indi- cates arsenic; if the precipitate be sky-blue, no arsenic is present.