1 This alkaloid is not to be confounded with another substance also (most unwisely) named papaverine, which exists in the unripe poppy capsule. The latter is a resinoid body.

Thebaine, C19H11NO4 crystallizes in silvery, four-sided scales, or in needles, or in small and horny crystals. It is strongly alkaline in reaction, and strongly electro-negative on friction. It is almost entirely insoluble in water, and in aqueous solutions of ammonia or alkalies; freely soluble in alcohol and ether, and rather less so in benzol. Dilute acids dissolve it easily, and form salts which will crystallize out of an alcoholic or an ethereal solution, but will not crystallize from a watery one. Concentrated acids, and also chlorine and bromine, have each the power to change thebaine into a resinoid body. Concentrated sulphuric acid dissolves it blood-red, the color afterward changing to yellow. The taste of thebaine is sharp and styptic rather than bitter.

Opianyl or meconine, C10Hl0O4, forms tasteless, white, shining needles, not easily soluble in cold water; soluble in ether, alcohol, and acetic acid. It dissolves without color in pure sulphuric acid, but, on heating the solution, it becomes purple.

The above-named substances are the really important components of opium, so far as present knowledge goes, described with just sufficient detail to allow of their physical and chemical identification. So much seemed absolutely necessary, but to go farther into the vast subject of the chemistry of opium would be foreign to the scope of the present work.

Physiological Action (A) of Opium, and (B) of its In

Dividual Ingredients. - It is necessary to consider these divisions separately. (A.) The physiological action of opium given in poisonous doses presents somewhat different aspects according to circumstances. Where the quantity is very large, and the forms such as to permit rapid absorption of the whole, the course of symptoms is as follows: - the patient, if an adult, quickly becomes conscious of a sense of fulness in the head, which seems to commence in the nape of the neck, and to spread therefrom; and in the course of a few minutes feels great and increasing drowsiness, and a sensation of general heat, which increases to an almost intolerable degree, and is then accompanied by sweating. This sweating, which generally bathes the body in moisture, tends to suspend all the other secretions, and is probably nature's medium for eliminating the poison. If the dose given has been very large, it reduces the surface to a clammy coldness. The drowsiness passes into semi-coma; the patient, unless aroused, lies unconscious, and is heedless of everything around him, but if roughly spoken to and shaken, can still be induced - though the speech is thick and hesitating - to answer questions, and even to get up and walk about; on leaving him, however, he immediately subsides into his former stupor. The pupils are generally contracted to the size of a pin's point, and become insensible to light, and there is buzzing in the ears. The pulse, which in the first or hot stage was rapid and somewhat full, becomes feeble and irregular, and falls to the normal rate, or even below it; simultaneously with this alteration, the features become pinched and ghastly, and flushing gives place to livid pallor, while the muscles of the limbs are affected with spasmodic jerkings.

The mouth and fauces are dry, and there is commonly nausea, and often vomiting. The general depression of the system is marked. The respiration becomes more and more embarrassed; in the later stages the presence of a quantity of mucous secretion in the tubes makes itself known by the rattling sound of the breathing. The respiration comes to a standstill usually some minutes before the entire cessation of the heart's action. Death, that is to say, takes place by apncea.

The course of events differs considerably in young children, especially in young infants. Here there is a more rapid passage into profound stupor; but what is specially characteristic is the much greater frequency with which convulsions occur. The convulsive movements vary from mere twitchings of the facial muscles to rhythmical startings of the limbs; to severe clonic convulsions, which may be hemiplegic, or may affect both sides of the body alike; and even to tetanic spasms.

I have seen three adults thrown into a state of apparently complete tetanic rigidity of the whole body, the mouth open and squared, all the facial muscles highly tetanized, the spine strongly curved, resembling the shape of a well-drawn bow; and this state of opisthotonos continue in each case, without any abatement, from twelve to forty-eight hours, and then only become relaxed to become rigid again for a longer or shorter time, according as the effect of the opium was kept up.

One of the patients remained more or less in this state for four or five weeks, opium having been given in the first instance to relieve toothache, and continued for the convulsive spasms which followed. As soon as the opium was discontinued, the patient recovered; but some months afterwards, having accidentally again taken opium, the same results quickly reappeared.

It is very interesting to note that this same tendency to convulsive movements under opium-poisoning, which in the European human race is almost limited to the first few years of life, is, in many of the lower animals, a regular feature of profound opium-poisoning.

Among the other exceptional poisonous effects of opium must be reckoned a singular action which it exerts upon the skin of certain patients, especially that of elderly ones. In such individuals an intense irritation of the skin, with intolerable itching, and sometimes even the production of a sudaminous rash, has been observed; these effects resulting both from the external and from the internal use of opium.

B. Physiological Action of Individual Opium Salts.