Active Ingredients. - A large number of substances enter into the composition of opium, and of some of these the physiological action is by no means settled. The most practically important are the alkaloids morphia and codeia, which exist in combination with meconic acid, an inert ingredient of which nothing further need be said. A third alkaloid, more or less resembling these in properties, but the action of which is not so accurately known, is narceia. Somewhat analogous to them, but rather intermediate in properties between these three and the group to be next mentioned, is papaverine. In strong contrast to the alkaloids, on which depend the properties of opium that are most familiarly known, stand narcotine and thebaia; the former of these being an antispasmodic tonic in small doses, and producing convulsions and death when given in large quantities; while the latter is apparently useless in very small doses, and a violent tetanizing poison when given in about the same quantity as would constitute a fatal dose of strychnia. Lastly, there is meconine, or opianyl, which has lately attracted some notice as a hypnotic.

As less important constituents of opium may be mentioned opianine, porphyroxine (or opine), cryptopine, rhoeadine, papaverosine, and the-bolactic acid.

Morphia, C17H19NO3 + H1O (that is, with one atom of water of crystallization) forms small white silky needles; or (if slowly crystallized out of alcohol) colorless, semi-transparent, six-sided, oblique, rhombic prisms. It has a distinctly alkaline reaction, and a bitter taste, but no smell. It melts at about 130° C, and a higher degree of heat destroys it. It is soluble in about 1,000 parts of cold, or 400 parts of boiling water; much more soluble in chloroform and in alcohol; insoluble in ether. It completely neutralizes the acids, forming salts which are, for the most part, crystallizable, odorless, bitter, soluble in water and in alcohol, but insoluble in ether, chloroform, and amylic alcohol. Nitric acid dissolves morphia with effervescence, producing a rich orange color; perchloride of iron strikes a deep indigo blue, turning to green when the reagent is added to excess; strong sulphuric acid and bichromate of potash produce a green tint, owing to reduction of oxide of chromium. These reactions are due to the deoxidizing power of morphia. Morphia itself is not employed medicinally.

Of the salts of morphia four are used in medicine - the acetate, muriate, sulphate, and bimeconate. The acetate, when carefully crystallized, presents bushy groups of silky needles; it is highly soluble in water (1 in 24), and evolves an acetous odor. The muriate occurs either in the form of groups of silky needles, or of large transparent prisms; it dissolves in 20 parts of cold water, 80 of cold alcohol, and 19 of glycerine. The sulphate forms bushy groups of needles that are soluble in 2 parts of water. The bimeconate (the form under which morphia exists in opium) is a resi-noid body.

Codeia, C15H11'NO3, is a powerful base, capable of precipitating the solutions of the salts of iron, lead, nickel, copper, and cobalt. It crystallizes out of a pure ethereal solution in small colorless crystals, which are without water; they melt at 150° C, and crystallize again on cooling. From a watery solution codeia separates in crystals which contain water; and, if the process be slow, forms large, regular, transparent octahedra, and right rhombic prisms; these part with their water of crytallization at 100° C.; in boiling water they melt into an oily fluid, odorless, and of a weakly bitter taste. Codeia is soluble in 17 parts of boiling and 80 parts of cold water; easily soluble in alcohol, chloroform, and ether. Codeia salts are mostly crystalline, have an exceedingly bitter taste, and are almost insoluble in ether. Two are used in medicine besides the alkaloid itself - viz., the muriate and the nitrate. The muriate crystallizes out of dilute solutions, in star-shaped groups of short needles; it is soluble in 20 parts of cold, and less than one part of boiling water. The nitrate crystallizes out of boiling water in small prisms, which melt under heat, and cool again into a resinoid mass.

Narceine, C23H19NO9, crystallizes from its solutions in water, alcohol, or dilute acetic acid, in long, white four-sided rhombic prisms, or clusters of fine needles, which have a taste at first bitter and then styptic; these melt at a high temperature and solidify amorphously on cooling. They are very insoluble in water, slightly soluble in cold, and easily so in boiling alcohol. Narceine dissolves in weak mineral and vegetable acids, if pure, without discoloration; if impure, often with a blue tinge. Although a weak base, it forms salts with these acids. Concentrated sulphuric acid first colors narceine brown, and then forms a bright yellow solution; concentrated nitric acid forms with it a yellow solution.

Papaverine,1 C20H11NO4, crystallizes out of alcohol in white, confusedly heaped-up needles or scales. It is very weakly alkaline in reaction. It is almost insoluble in water, and but little soluble in cold alcohol or ether; boiling alcohol takes it up freely; chloroform extracts it with facility either from an acid or an alkaline watery solution. Concentrated sulphuric acid changes papaverine instantly to a deep violet blue, and forms a violet solution, the color of which fades very slowly. Papaverine salts are mostly difficult of solution in water.

Narcotine, C22H13NO3 crystallizes out of an alcoholic or ethereal solution in colorless, transparent, pearly prisms, or grouped needles on the right-rhombic system: precipitated by an alkali from an acid solution, it presents the form of light white flakes. It is odorless, tasteless, and neutral in reaction. Cold water hardly dissolves it; boiling water only in very small proportion. It is moderately soluble in alcohol and in ether; chloroform dissolves it with great facility. Its neutral solutions rotate the plane of polarization to the left; its acid solutions rotate the plane to the right. With acids, narcotine forms salts of acid reaction; usually un-crystallizable; soluble in water, alcohol, and ether; and extremely bitter to the taste. Concentrated nitric acid converts it into a red resinoid body, red vapors being also given off; this resin, on boiling with potash, develops methvlamine.