OPIUM, in chemistry and medicine, an inspissated gummy juice, which is ob tained from the head of the " papaper somniferum." It is imported from Per sia, Arabia, and other warm parts of Asia, in flat cakes, covered with leaves to pre vent their sticking together. It has a reddish brown colour, and strong pecu liar smell : its taste at first is nauseous and bitter ; but this soon becomes acrid, and produces a slight warmth in the mouth. A peculiar substance has been detected in opium, to which it is suppos - ed the properties it possesses of pro ducing sleep are owing. On account of this property, this substance has receiy ed the name of narcotic matter. It is obtained from the milky juices of some plants, as those of the poppy, lettuce, and some others. Opium, which is ex tracted from the poppy, is prepared by the following process. The heads of the white poppy, which is cultivated in dif ferent countries of the east for this pur pose, are wounded with a sharp instru ment; a milky juice flows out, which concretes, and is collected and formed in to cakes. In this state opium is a tenacious substance, of a brownish colour; has a pe culiar smell, and a disagreeable bitter taste. It becomes soft with a moderate heat. It readily takes fire, and burns rapid ly. By the analysis of opium, it appears to be composed of the sulphates of lime and of potash, extractive matter, gluten, mu cilage, resinous matter, and an oil, be sides the narcotic matter, to which its pe culiar properties are owing. By digest ing opium in water, part of it is dissolv ed, and by evaporating the solution to the consistence of syrup, a gritty precipitate appears, which becomes more eopious with the addition of water. This preci pitate is composed of resinous and ex tractive matter, besides the peculiar cotic matter which is crystallized. When alcohol is digested on this precipitate, the resinous and narcotic matters are dissolv ed, and the extractive matter remains behind. As the solution cools, the nar cotic matter crystallizes ; but the crystals are coloured with a portion of resin. By
repeated solutions and crystallizations it may be obtained tolerably pure. If alco hol be digested on the residuum, it be comes of a deep red colour, the same crystals are deposited on cooling, and may be purified in the same way from the resinous matter with which they are contaminated. The narcotic matter, when properly purified, is of a white colour ; crystallizes in right-angled prisms, with a rhomboidal base ; and has neither taste nor smell. It is insoluble in cold water, and requires 400 parts of boiling water for its solution, from which it is precipi tated by cooling. The solution does not redden the tincture of turnsole. It is soluble in 24 parts of boiling alcohol, and requires about 100 parts when it is cold. When water is added to the solution in alcohol, it is precipitated in the form of a white opaque matter. One of the most decided characters of this substance is its easy solubility in all the acids, and without the aid of heat. It is precipitated from these solutions by means of an alkali, in the form of white powder. Pure alkalies increase the power of its solubility in wa ter, and the acids, when not added in ex cess, occasion a precipitate. When nitric acid is poured on the crystals reduced to a coarse powder, it communicates to them a red colour, and readily dissolves them. When the solution is heated and evaporated, it yields crystals of. oxalic acid in considerable quantity. The resi duum has a very bitter taste. From the effects of heat and of nitric acid on this substance, it appears to be composed of oxygen, hydrogen, carbon, and azote This narcotic substance is also found in the milky juice, and in the extracts which are obtained from several other plants, as from different species of lac tuca, or lettuce ; hyoscyamus niger, or henbane. The leaves of some plants also produce similar effects, as those of the deadly night-shade, fox-glove, and conium maculatuin, or hemlock. See Poser.