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
Catalogue details

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.

    63/1180 (page 31)
    temperature of 150° F. being sufficient for this process. In this way refined sesquicarbonate of ammonia is obtained. If sal ammoniac (chloride of ammonium) be employed, the decomposition in this process maybe represented thus: 2NH4Cl + CaC03=(NH4)2C03 + CaCl2, but in the act of undergoing vaporisation part of the salt suffers decomposition ; ammonia, NH3, and water, H20, are lost, and the compound which condenses presents on an average the com- position which is approximately represented by the pharmacopoeia formula. It is generally regarded as a mixture of two molecules of Bicarbonate of Ammonia, 2[ini4HC03] and one molecule of Carbamate of Ammonia, (NH3)2C02 Sesquicarbonate of ammonia cannot be resublimed, unchanged ; hence in the process of refining its constitution is altered, and the proportion of the constituent elements varies according to the manner of conducting the process. Properties.—When exposed to the air it evolves carbamate of ammonia (NH3,C02 or (NH3)2C02), leaving a residue of bicar- bonate (NH40,2C02,HO or H2TH4C03); so that its vapour has a pungent odour, and strongly reddens turmeric paper. The resulting bicarbonate is opaque, pulverulent, and much less pungent, from which it has been termed mild carbonate of ammonia. Carbonate of ammonia is soluble in four times its weight of cold water; but boiling water or alcohol decomposes it, with the evolution of car- bonic acid. Impurities.—The carbonate of ammonia of commerce is sometimes contaminated with empyreumatic oil, and in this state it yields a more or less deeply-coloured, or even blackish, solution when dis- solved in dilute acid. The pure salt, on the other hand, yields a colourless solution. If any hyposulphite of ammonia be present, the salt, when neutralised by acetic acid, yields with the nitrate of silver a precipitate which is at first white, but becomes black. The pre- sence of lead (derived from the leaden receivers used in its manu- facture) is recognised by dissolving the salt in diluted nitric acid, and testing with sulphuretted hydrogen, which produces a dark or black colour or precipitate, if lead be present. Physiological Effects.—In small doses it proves antacid, stimulant and sudorific, usually increasing the frequency of the pulse. By repeated use it operates as a resolvent or liquefacient spansemic, like the other alkalies, though much less intensely so. In doses of thirty grains or more it is apt to occasion vomiting. The effects of an over-dose are abdominal pains, and other symptoms of inflammation, convulsions, and other phenomena indicative of its action on the nervous system.