Foods, their composition and analysis : a manual for the use of analytical chemists and others with an introductory essay on the history of adulteration / Alexander Wynter Blyth.

  • Blyth, Alexander Wynter, 1844-1921.
Date:
1888
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Licence: Public Domain Mark

Credit: Foods, their composition and analysis : a manual for the use of analytical chemists and others with an introductory essay on the history of adulteration / Alexander Wynter Blyth. Source: Wellcome Collection.

    608/734 (page 552)
    Another special method used for the detection of nitrobenzine was proposed by Maisch:—1 grm. of the essence is dissolved in twelve times its volume of alcohol, -75 of caustic melted potash is added, and the whole heated until the liquid is diminished to about one-third. The pure essence, on cooling, is of a light brown colour, and dissolves entirely in water; but if nitroben- zine is present, the residue is brown, crystalline, and insoluble in water. The action of sodium on the essence may also be utilised as a test:—Pure almond essence, when treated with sodium, gives white flocks; if nitrobenzine should be present, the sodium is immediately covered with yellow or brown flakes, according to the amount of adulteration; if the percentage rises as high as 0-30 to 050, the whole liquid after a minute becomes thick and opaque. (Dragendorff.) However, the action of potash alone on a sample adulterated with nitrobenzine is tolerably conclusive. If one grm. of the essence is treated in a test-tube with half its weight of pure caustic potash, a yellow coloration is produced, should the essence be pure; but if nitrobenzine be present, the tint soon becomes yellowish-red, and at the end of a minute green. On the addition of a little water, the mixture separates into two layers, of which the lower is yellow and the upper green, the latter changing in the course of a day into red. Most foreign ethereal oils may be detected by the bisulphate of soda test:—If a little of the pure essence be dropped into a warm solution of this salt, of from 1-24 to l-26 specific gravity, shaken, and then diluted with hot water, it is fully dissolved; other essences, on the contrary, are insoluble. BIBLIOGRAPHY. Bette.—Ann. Chem. Pharm., xxi. 211. Bourgoin.—Falsification de l’essence d’amandes amSres par le nitrobenzole? Journ. Pharm. et Ghim., 4e serie, 1872, t. xv., p. 281. Fluckiger.—AT. Jahrb. Pharm., xxxiv. 202; Testing of Bitter Almond Oil, Pharm. Journ., Oct., 1870, p. 321. Hirsch—“Die Priifung der Arzneimittel.” Berlin, 1S75. Hgsemann.—“Die Pflanzenstoffe.” Berlin, 1871. Lehmann.—Proc. Amer. Pharm. Assoc., 1875, 437. Maisch.—Falsification de l’essence d’amandes ameres. Journ. Pharm. et Chim., 3e serie, 1858, t. xxxiv., p. 75. Redwood.—Means of recognising the Purity of Essence of Almonds. Pharm. Journ., and Journ. Pharm. et Chim., 185S. _ Robiqdet and Boutron Ciiarlard.—Ann. Chem. Phys. [2], xliv. 35- Journ. Pharm., [2], xxiii.; Ann. Chem. Pharm., xxxi. 211.