This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
The bulk of the opium normally imported into England consists of the Turkey and Persian drugs; the latter is largely exported to South America and elsewhere for smoking, but when sufficiently cheap is •used for the manufacture of morphine.
Indian Opium. The chief opium-producing districts in India are the central districts of the Ganges, including Behar, Benares, and Patna, and the tablelands of Malwa which lie to the north-east of Bombay, most of the drug being produced by licensed cultivators and purchased by the Government. That which is destined for use in India is dried in the sun until the moisture in it is reduced to 10 per cent., and then made into flat cakes (Bengal abkari opium) or round balls (Malwa opium) and wrapped in oiled paper. For the Chinese market it is formed into round balls which are enveloped in cases made of dried poppy petals, opium, and water, each cake with its shell resembling a Dutch cheese in size and shape.1
1 Details, of the process will be found in the Pharmacographia Indica.
During the war large quantities of Indian opium were imported into this country in the form of a uniform, black, paste, in flat cakes of 2 lb. wrapped in waxed paper.
Amongst the numerous constituents of opium the most important are the alkaloids it contains. Of these no fewer than twenty-one have been reported, but the existence of some of these in the drug is open to considerable doubt. Chief of them, both in its medicinal importance and in the quantity in which it exists, is morphine; narcotine and codeine are of secondary importance, and next to these come thebaine, narceine, and papaverine.1
forms colourless crystals, very slightly soluble in cold water but readily in solutions of caustic alkalies or alkaline earths; it is almost insoluble in cold ether, chloroform, or benzene. Heated with hydrochloric acid in a sealed tube to 140°-150°, it is partly converted into apomorphine (C17H17N02). Morphine is a powerful hypnotic, but apomorphine, in addition to a hypnotic action, produces a powerful emetic effect.
Codeine, C18H11N03, or methyl morphine is usually obtained from the mother liquors from which morphine has been crystallised, but can also be prepared by methylating morphine. It forms large rhombic crystals soluble in 80 parts of water and readily soluble in chloroform. It is a strong base, and is liberated from its salts by fixed alkalies, but not by ammonia. It has only a mild hypnotic action.
Narcotine, C22H13N07 or C19H14(OCH3)3N04, crystallises readily in rhombic prisms or needles, and may be extracted from the residue left after treating opium with water; it is a weak base and has little or no narcotic action, hence it has also been called ' anarcotine.'
All these are well-defined, crystalline alkaloids, and together constitute in good dry opium about one-fifth of the weight of the drug.
Amongst the other constituents attention must be directed to meconic acid, HC7H307,3H10, a crystalline organic acid that exists to the extent of about 5 per cent. combined with morphine; this well-characterised and easily identified acid is important in toxicological investigations as corroborative of the presence of opium.
Meconin and meconoiosin are two indifferent substances and exist in small quantity only.
Mucilage, sugar, wax, caoutchouc, and salts of calcium and magnesium are also contained in opium, but starch, tannin, oxalic acid, and fat, all of which are common constituents of plants, are not found in it, and their presence therefore indicates adulteration of the drug. . The proportion of water contained in freshly imported Turkey opium varies from 7 to 35 per cent. Good Turkey opium yields from 4 to 8 per cent, of ash and from 55 to 65 (usually over 60) per cent, of dry aqueous extract (calculated in each case upon the dry opium).
1 For a complete list and a table of the reactions by which they may be distinguished, Henry's Plant Alkaloids, p. 199, may be consulted.
The quality of opium is, however, determined almost exclusively by the proportion of morphine it contains. Good Turkey opium yields from about 12 to 22 per cent. of anhydrous morphine (calculated upon the dry drug), but is subject, of course, to considerable variation. Persian opium is less rich in morphine, and contains, when of good quality, from 8 to 12 per cent; in exceptional cases 16 and even more per cent, has been recorded. Indian opium varies from 3 to 15 per cent., the bulk ranging from 7.5 to 10 per cent. Efforts have been and are being made to raise the morphine content of this variety. Chinese opium has been shown to contain from 4.3 to 11.2 per cent. The alkaloid certainly exists in combination with acids (probably partly with meconic, partly with sulphuric acid), and is easily and completely extracted by water.
Narcotine varies usually from about 2 to 8 per cent., although the latter figure is occasionally exceeded. It appears to occur in larger proportion in Indian and Persian opium than it does in Turkey, and to exist chiefly in the free state, it being a weak base. Codeine exists in proportions ranging from 0.3 to 4.0 per cent, in combination with acids. Thebaine varies from 0.2 to 0.5 per cent., narceine from 0.1 to 0.4 per cent. The remaining alkaloids constitute together about I per cent, of the drug.
For the preparation of tincture and extract of opium which are standardised to contain 1 percent, and 20 per cent, of morphine respectively, any suitable variety of opium may be used provided it contains, when dry, not less than 7.5 per cent, of anhydrous morphine, but for other official uses opium must contain between 9.5 and 10.5 per cent, of morphine, and opium containing more than 10 per cent, may be diluted with opium containing between 7'5 and 10 per cent, or with milk sugar. Hence any opium containing over 7.5 per cent, of morphine may be officially used, the strength being adjusted by suitable blending. This permission was apparently given with the view of favouring the importation of the best varieties of Indian opium. Turkey opium, on the other hand, is occasionally diluted to contain about 10 per cent, of morphine before exportation.
The necessarily high price of the drug and its nature invite adulteration. Stones, small shot, pieces of lead, and such substances have been found in opium. Gum, grape must, sugary fruits, etc, are said to be added to it. Persian opiim frequently contains added gum and sometimes also mineral matter (clay). The percentage of morphine, the ash, moisture, and residue insoluble in water all give valuable indications, the last-named excluding the sugary pulp of apricots and other fruits. The insoluble residue will contain portions of the outer epidermis of the poppy capsule, but not of the inner (absence of powdered capsules); such fragments are more frequent in Turkey than in Indian opium, the former, obtained usually from a horizontal incision, requiring more scraping than the latter, in which the opium collects at the bottom of a vertical incision. Starch should not be present in appreciable quantity; it is, however, regularly found in Persian opium (Mjoen, 1895), and traces are said to be frequently present in Turkey opium (Caesar and Loretz, 1898) but not in quantity sufficient to constitute an adulteration.