Chemistry : general, medical and pharmaceutical :including the chemistry of the British Pharmacopoeia : a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield.

  • Attfield, John, 1835-1911.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry : general, medical and pharmaceutical :including the chemistry of the British Pharmacopoeia : a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

    818/930 (page 776)
    because, for educational purposes, pure nitre is under ex- amination. Only after analyses of pure substances have yielded the operator results practically identical with those by calculation, can analyses of substances of unknown de- gree of purity be undertaken with confidence. A table of atomic weights, from which to find molecular weights, is given in the Appendix. 01 = 35-5, or, more exactly, 35-4. Platinum Residues should be preserved, and the metal recovered from them from time to time {vide p. 288). Hot alcohol sometimes reduces perchloride of platinum, the metal being thrown out of solution m a finely divided form, known as platinum black; only aqueous solutions, therefore, of the salt should be used where heat is employed. Hence, also, in washing out excess of perchloride of platinum from the double chloride of platinum and potassium by spirit, the application of heat should be avoided. Effervescing Potash-water {Liquor Potassaz Efervescens, B P) is most easily estimated volumetrically (p. 748). Any adulteration by an equivalent amount of bicarbonate of sodium would, however, by that process be undetected, hence the Pharmacopoeia directs that five fluid ounces eva- porated to one-fifth and 12 grains of tartaric acid added yield a crystalline precipitate, which when dried we^te not less than 12 grains/' Five fluid ounces of this preparation C d contain V5 grains of bicarbonate convertible mto 14-1 grains of acid tartrate of potassium by 11-25 g, ains of tartaric acid. The method is somewhat efficient for » potash-water containing nothing but bicar- bonate of alkali-metals. Proportional Weights of Equivalent Quantities of Potassium and its Salts. v .... 78 Metal un 94 Oxide (Potash) . . • • • **0 • ■ • • Hydrate (Caustic Potash) . 2KHO . • 13g Carbonate fanhydrous| . . . ^3 • • • • • Carbonate (crystalline) . . • W10/Aq. Bicarbonate 2KNO ' ' ■ 202 Nitrate salt' ptci4>oi. . . . ^ Platinum