Opium Pharm. Lond. & Edinb. Opium: a concrete gummy-refinous juice; somewhat soft and tenacious, especially when much handled or warmed; of a dark reddish brown colour in the mass, and when reduced into powder yellow. It is brought from Egypt, Persia, and some other parts of Asia, in flat cakes or irregular masses, from four to about sixteen ounces in weight, covered with leaves to prevent their sticking together.

It is extracted from the heads of white poppies (see Papaver) which in those countries are cultivated in fields for this use. Kaempser reports, that the heads, when almost ripe, are wounded with a five-edged instrument, by which as many parallel incisions are made at once from top to bottom; that the juice which exudes is next day scraped off, and the other sides of the heads wounded in like manner; and that the juice is afterwards worked with a little water, till it acquires the consistence, tenacity, and brightness of the finest pitch. The best opium was formerly called Thebaic opium, from its being prepared about Thebes in Egypt: no distinc-tion is now made in regard to the places of its production, though the epithet thebaic serves to distinguish some of its officinal preparations.

Opium has a faint disagreeable smell, and a bitterish, somewhat hot, biting taste. Watery tinctures of it strike a black colour with chalybeate solutions, and thus seem to discover some aftringency. Mixed with the serum of blood, they thicken and render it whitish; and on blood itself, newly drawn, they have nearly a like effect! Mr. Eller observes, that on examining with a microscope blood thickened by a vinous tincture of opium, the nature of its globules seemed to be destroyed. But neither from these, nor any of the other known sensible properties of this drug, can its surprizing operation in the human body be deduced.

Taken in proper doses, it commonly procures sleep, and a temporary respite from pain, or the action of any stimulating power. The cause of the pain it in many cases confirms or augments; and in not a few, it fails even of giving palliating relief. The cases in which it is proper or improper will be best understood from a view of its general effects; which, so far as experience has hitherto discovered them, are the following.

It renders the solids, while the operation of the opium continues, less sensible of every kind of irritation, whether proceeding from an internal cause, or from acrimonious medicines, as cantharides, and the more active mercurials, of which it is the best corrector - It relaxes the nerves; abating or removing cramps or spasms, even those of the more violent kind; and increasing paralytic disorders and debilities of the nervous system - It incraffates thin serous humours in the fauces and adjacent parts; by which means, it proves frequently a speedy cure for simple catarrhs and tickling coughs; but in phthisical and peripneumonic cases, dangerously obstructs expectoration, unless this effect be provided againsl by suitable additions, as am-moniacum and squills - It produces a fulness and distention of the whole habit; and thus exasperates inflammations both internal and external, and all plethoric symyptoms - It promotes perspiration and sweat; but restrains all other evacuations, unless when they proceed from a relaxation and insensibility of the parts, as the colliquative diarrhoeas in the advanced Stage of hectic fevers - It promotes labour-pains and delivery (a) more effectually than the medicines of the Stimulating kind usually recommended for that purpose; partly perhaps by increasing plenitude, and partly by relaxing the solids or taking off spasmodic Strictures - And indeed all the preceding effects are perhaps consequences of one general power, being nearly allied to those which natural sleep produces (b). The operation of opium is generally accompanied with a slow but strong and full pulse, and a slight redness, heat and itching of the skin: it is followed by a weak and languid pulse, lowness of the spirits, some difficulty of breath-ing or a sense of tightness about the breast, a slight giddiness of the head, dryness of the mouth and sauces, and some degree of nausea. Given on a full stomach, it commonly occasions a nausea from the beginning, which continues till the opium is rejected along with the contents of the stomach. Where the evacuation of acrid humours, accumulated in the first passages, is suppressed by it, great sickness and uneasiness are generally complained of, till the salutary discharge either takes place again spontane-ously or is promoted by art.

(a) Mead, Monita & praecept. med, p. 253.

(b) See Young's treatise on opium.

An over dose occasions either immoderate mirth or stupidity, a redness of the face, swelling of the lips, relaxation of the joints, vertigo, deep sleep with turbulent dreams and startings, convulsions, and cold sweats. Geof-froy observes, that those who recover, are generally relieved by a diarrhoea, or by a pro-fuse sweat, which is accompanied with a violent itching. The proper remedies, besides emetics, blisters, and bleeding, are acids and neutral mixtures: Dr. Mead says he has given, with extraordinary success, repeated doses of a mixture of salt of wormwood with lemon juice.

A long continued use of opium is productive of great relaxation and debility, sluggifhness, heaviness, loss of appetite, dropsies, tremors, acrimony of the humours, frequent stimulus to urine, and propensity to venery. On leaving it off after habitual use, an extreme lowness of the spirits, languor, and anxiety, succeed; which are relieved by having again recourse to opium, and in some measure by spirituous or vinous liquors.

With regard to the dose, one grain is generally a sufficient, and sometimes too large a one: maniacal persons, and those who labour under violent spasms, require oftentimes two, three, or more grains; though even in these cases, it is generally more advisable to repeat the dose at proper intervals, than to enlarge it. By frequent use, much greater quantities may be borne: the Turks, who habituate them-selves to opium as a succedaneum to spirituous liquors, are said to take commonly a dram at a time, and Garcias says that he knew one who every day took ten drams.