The hygroscopic moisture ranges in different samples from 10 to 13 per cent. The writer analysed several samples of genuine cayenne, and the mean of these analyses was as follows: Hence the ash of cayenne should not exceed 6 per cent.; it should yield at least one-quarter of its weight to alcohol, and from 9 to 10 per cent. to ether. § 306. The Adulterations of Cayenne usually enumerated are: all kinds of red mineral powders, from brick-dust to cinnabar, and a few starches. There does not appear, however, to have been any conviction recently for the adulteration of cayenne, and the numerous samples the writer has examined were all genuine. Most of these additions would be easily detected in the ash, or by the microscope. Cinnabar is highly improbable; for its detection, see " Mercury," in the second volume of this work. BIBLIOGRAPHY. BLYTH, A. WYNTER.-Art. Capsicum, "Dict. of Hygiène.” THRESH, J. C.-Pharm. Journ., [3], 309, p. 941; [3], 315, 1876, p. 21; [3], THE SWEET AND BITTER ALMOND. § 307. The sweet almond, the seed of Amygdala communis, and the bitter almond, the seed of Amygdalus communis, var. Amara, enter either in whole or in part into so many articles of food (such as sweetmeats and pastry, and as a flavouring ingredient into certain drinks), that it is absolutely necessary to be acquainted with their chemical composition. Both varieties of almond agree in containing about 50 per cent. of a bland fixed oil (consisting chiefly of olein, and liable to become rancid), as well as an albuminous principle, emulsin, sugar, gum, and woody fibre; but only in the bitter almond is found, in addition to the foregoing, amygdaline. § 308. The Oil of Almonds is a thin fluid oil, of a clear yellow colour, specific gravity 0·914 to 920, not coagulated by a cold of - 10°; at -16° it becomes cloudy, and at -22° it solidifies to a white butter. Oil of almonds appears to be rather frequently adulterated with other oils. 2.5 drops of the oil, shaken with an equal bulk of nitric acid (specific gravity 1.20) and bisulphide of carbon, should not show any colour after standing a few minutes; if it becomes within half an hour yellow, or reddish-yellow, the change indicates oil from cherry or apricot kernels. The following test will detect drying oils :-Dissolve one part of starch in 3 parts of warm nitric acid, of 1.20 specific gravity, and warm in a capacious vessel over the water-bath with 10 parts of almond oil, until all evolution of gas ceases. The oil after cooling is within two days changed into a warty, crystalline, greasy mass of elaidin. Should it, however, contain a drying oil (poppy, for example), it either remains quite fluid or semi-fluid, according to the proportion of the adulterant present. The colour of the elaidin is also a guide; that produced by the sweet almond is pure white, by the bitter, yellowish-white, and by the small or inferior kinds of almonds, brownish-yellow; if the elaidin should be red, it denotes adulteration of some foreign oil, especially of sesame. Pure almond oil dissolves in 25 parts of cold and 6 of hot alcohol. The above tests, and in addition the low temperature required for congelation, should detect all ordinary adulterations. $309. Amygdaline (CHNO) is a glucoside, discovered in 1830 by Robiquet and Boutron-Charlard. It may be extracted from almond-cake by boiling alcohol of 95 per cent., and then precipitated from the somewhat concentrated alcoholic solution by ether. Amygdaline* crystallises from 80 per cent. alcohol in colourless glittering scales, containing two atoms of water: it can also be obtained in crystals. Amorphous amygdaline of the before-mentioned cherry-laurel leaves and buckthorn bark is best obtained by the following method:-The dried buckthorn bark is boiled with absolute alcohol, agitated with lead oxide, and evaporated to dryness. Dried in a vacuum over 804H, it forms a brittle, yellow, transparent, resin-like mass, which, when heated to 100°, becomes dark-brown; it can be dissolved by boiling alcohol and by water, but is insoluble in ether. Although amorphous, it is a crystalloid with three atoms of water, as proved by dialysis from water or weak spirit, but in such a case it loses one atom if dried over sulphuric acid. At 100° to 120° it may be obtained anhydrous. Amygdaline possesses no smell; it has a slightly bitter taste; its reaction is neutral, and it polarises to the left [a] r= - 35.57°. It dissolves in all proportions in boiling water, and in 12 parts of cold of 10°; requires 148 parts of alcohol, specific gravity 0-939, 904 parts of alcohol, specific gravity 0-819, if cold-but if boiling, 11 parts of the first and 12 of the last; it is insoluble in ether. It melts at 120°, and begins to carbonise at 160°, when it develops a caramel smell, and is at length fully destroyed. * Lehmann, in his recent elaborate researches, found the method of Liebig and Wohler the best for obtaining crystalline amygdaline. The process consists in boiling the substance with strong alcohol (of 94 to 95 per cent.) twice successively, after having first removed the fixed oil by petroleum benzine, concentrating to about one-half or one-sixth of its volume; and then adding ether, which precipitates the amygdaline, and removes any of the remaining fixed oil. Lehmann obtained from Both of these latter substances contain hydrocyanic acid ready formed. Amygdaline, by the action of dilute hydrochloric acid, splits up into glucose and mandelic acid, volatile oil of almonds, and formic acid. If boiled with solutions of potash or baryta it forms ammonia and amygdalic acid. The most interesting decomposition is, however, that which takes place by the action of emulsin; it then breaks up into volatile oil of almonds, hydrocyanic acid, and formic acid. (See Prussic Acid, in the second volume of this work.) Volatile Oil, or Essence of Almonds, does not exist as such in the bitter almond; it is, as above explained, the result of the decomposition of the amygdaline. The oil of almonds, when properly purified from prussic acid, is identical with the hydride of benzole, CH.OH. It is colourless, thin, turning a ray of polarised light to the right, of a peculiar, pleasant odour, and a burning aromatic taste. Its specific gravity is 1.043 to 107, usually 1.06 (Hirsch). Its boiling point is 180°. By the action of light and air it is gradually oxidised into benzoic acid. It is soluble in equal parts of alcohol, 0.830 specific gravity, and in about 30 parts of water. The ethereal or volatile oil is officinal in the French, Swiss, and Norwegian pharmacopoeias. The ethereal oil is much adulterated. The analyst will specially look for alcohol, prussic acid, nitrobenzine, and ethereal oils. If alcohol-free, the addition of an equal weight of fuming nitric acid produces no effervescence, and after two or three days the mass becomes emerald green, and crystals of benzoic acid appear. On the other hand, if it contain alcohol from 0.08 per cent. upwards, there is immediately a strong effervescence. Some of the tests given for alcohol at pp. 375-376 may also be of service. The detection and estimation of prussic acid in the essence is carried out on the principles detailed in the article on Prussic Acid (see vol. ii.) Nitrobenzine is indicated when the essence is not entirely soluble in a solution of bisulphate of potash, and the specifie gravity is higher than 107, the specific gravity of nitrobenzine being 1-20 to 1.29; the boiling point will also be raised. In such a case nitrobenzine should be specially tested for, by changing it into aniline by reducing agents. For this purpose 10 parts of dilute sulphuric acid (specific gravity 1·117) may be added to 10 of granulated zinc and 1 part of the essence. At the end of two hours (after frequent agitation) the fluid is passed through a moistened filter, and a crystal of chlorate of potash added to the filtrate with a drop of concentrated sulphuric acid. If a violet or red colour is produced, it is due to the presence of an aniline salt, produced from nitrobenzine; but if there is no coloration, nitrobenzine must have been absent. 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 nitrobenzine 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 0:50, 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 1.26 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 amères par le nitrobenzole? Journ. Pharm. et Chim., 4e série, 1872, t. xv., p. 281. FLUCKIGER.-N. Jahrb. Pharm., xxxiv. 202; Testing of Bitter Almond Oil, Pharm. Journ., Oct., 1870, p. 321. HIRSCH "Die Prüfung der Arzneimittel." Berlin, 1875. HUSEMANN.-"Die Pflanzenstoffe." Berlin, 1871. MAISCH.-Falsification de l'essence d'amandes amères. Journ. Pharm. et REDWOOD.-Means of recognising the Purity of Essence of Almonds. Pharm. Journ., and Journ. Pharm. et Chim., 1858. ROBIQUET and BOUTRON CHARLARD.-Ann. Chem. Phys. [2], xliv. 352 Journ. Pharm., [2], xxiii.; Ann. Chem. Pharm., xxxi. 211. |