A dispensatory, or commentary on the phgarmacopoeias of Great Britain.

  • Robert Christison
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: A dispensatory, or commentary on the phgarmacopoeias of Great Britain. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    The Colleges have all admitted a diluted muriatic acid for inter- nal use. It might have been desirable that the Colleges had not differed in the degree of dilution they recognize. The London and Edinburgh Colleges have adopted a preparation of convenient strength, consisting of one part by volume of acid to four of water, and about the density of 1050. The diluted acid of the Dublin College is too strong for convenience in dispensing. Adulterations.—Commercial muriatic acid, by reason of its ex- treme cheapness, is seldom adulterated intentionally. But it is subject to contain various impurities, which must be attended to in respect of certain pharmaceutic processes for which it is thus ren- dered unfit. It usually contains a little iron, generally however a mere trace. This is supposed by some to be the cause of its yel- low colour; but the colour is sometimes deep when the quantity of iron is so small as to be incapable of accounting for it. Iron may be detected by the blue colour and precipitate occasioned by ferrocyanate of potash in the neutralized acid. A more import- ant foreign ingredient is chlorine, derived from the presence of nitric acid in the sulphuric acid, or of a nitrate in the muriate of soda, and the consequent reaction of the nitric and muriatic acids on one another. This impregnation too has been supposed to oc- casion the colour of commercial muriatic acid; and it may be one cause. Yet some specimens strongly loaded with chlorine become colourless when distilled, although the impregnation of chlorine does not disappear, as some incorrectly allege, in the distilled li- quid. Chlorine is discovered by the acid dissolving gold leaf, especially when aided by a gentle heat; it is also indicated by the acid decolorizing the solution of sulphate of indigo; and both of these tests have been admitted by the London College. Sulphurous acid, also a frequent impurity, is detected by adding to half an ounce of the acid two drachms of crystallized proto- chloride of tin, and then diluting the mixture with two fluid- ounces of water. The presence of sulphurous acid is shown by the salt rendering the muriatic acid yellow, and the water ren- ders it brown, a brown precipitate of sulphuret of tin subsequently falling [Girardin].—The only other impurity of any consequence is sulphuric acid, which, being employed in preparing it, is apt to be spurted up into the beak of the retort, or carried over by too strong heat applied towards the close. It is known by the nitrate or muriate of baryta occasioning a white precipitate. Before using this test the acid must be diluted with four or five waters, other- wise a crystalline precipitate of muriate of baryta may be caused by the acid attracting the water in which the salt is dissolved. Saline matters are met with in some commercial acids, and when abundant must be regarded as intentional adulterations, probably introduced to increase the density. They are best detected by distilling the acid to dryness, and examining the crystalline resi- duum. The yellow colour of muriatic .acid has been ascribed by some to a trace of bromine j which appears an improbable explanation.
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