When the practitioner is called in to a case of poisoning while yet there is life, he must set himself to preserve it in whatever way he best can; in this of course he must be guided by circumstances, but several broad rules may be laid down. All have one end, but the order may be varied. That is best which is readiest, the grand rule being to lose no time. Most of the modes of treatment come under one or other of the three following heads:—1. Get rid of the poison. 2. Stop its action. 3. Remedy the mischief it has done.

1. To get rid of the poison is ordinarily the first thing to be done, but not always. To do so when the poison has been swallowed two means may be employed: vomiting or the stomach-pump.

The latter is one of the most certain means we possess of emptying the stomach; and by means of it this viscus may be washed out, and the antidote, if any be known, administered. In speaking hereafter, however, of the treatment to be adopted in each particular instance it will be seen that there are some cases, as poisoning by corrosives, in which this instrument cannot be used; as it might not only cause laceration of the tissues, but even perforation of the oesophagus or stomach. It is hardly necessary to mention that in all cases a certain tact is required in its employment; the tube having, on more than one occasion, been introduced into the trachea, and the lungs injected with water, &c. It is a good rule also to withdraw less fluid than is pumped into the stomach.

Supposing, however, that this instrument is not at hand, or that it is an improper occasion for its employment, recourse must be had to vomiting, natural or artificial. Vomiting is, in many instances, one of the first and most important signs of poisoning, especially by irritant substances. When such is the case, it is only necessary to foster the tendency by copious draughts of lukewarm water; but if there be no vomiting and the stomach pump be not at hand an emetic must be given. Of these remedies perhaps there is not one which can be generally used with so much advantage as the sulphate of zinc in scruple doses; for not only is it more rapid in its action, but its effects are less depressing than those of any others. This last recommendation will appear the more desirable when we remember that the absorption of poisons is promoted by all lowering measures; and consequently, bleeding, the exhibition of tartarised antimony, and the administration of drastic purgatives, ought to be avoided. In poisoning by opium and other narcotics, the sulphate of copper in eight or ten grain doses will often excite the stomach to act when other emetics have failed. Ipecacuan wine (six or eight drachms) is a useful agent in many cases; or if a warm stimulating draught be needed a scruple of powdered ipecacuanha, with the same quantity of the sesquicarbonate of ammonia, may be administered in a wineglassful of water. In the absence of these, mustard proves an excellent substitute; a teaspoonful or two being given in warm water, and frequently repeated. Even common salt may be used with good effect. Vomiting may also be excited by tickling the fauces, as well as by the free administration of warm water or of hot greasy water.

When the poison has been applied locally, to prevent its absorption, a ligature must be applied between the trunk and the wounded part, as near the latter as possible; while the deleterious substance is to be removed by free incisions and plentiful washings. Sucking by the mouth or by cupping-glasses may also be employed.

2. To stop the action of the poison if it cannot be readily and immediately removed.—The means whereby this is effected is ordinarily the administration of an antidote. As no universal antidote is known, the treatment will of course vary with the substance taken. This will be fully explained when speaking of each particular poison.

An antidote, according to Orfila, should possess the following properties:—It should be capable of being taken in a large dose without danger; it should act upon the poison, whether liquid or solid, at a temperature equal to or below that of the body; its action should be quick; it should be capable of combining with the poison, though shielded by the gastric juice, mucus, bile, or other substances contained in the stomach; and lastly, it should deprive the poison of its deleterious properties.

Antidotes mostly operate by forming harmless chemical combinations, or by producing insoluble compounds, and thus preventing or delaying absorption. In most cases they have no effect upon the constitution; but some may be looked upon as a kind of counter-poison. Thus, the antagonistic action of opium and belladonna seems fairly made out, and we might perhaps include under this head chloroform, as in some degree, an antidote to strychnia.

Dr. Garrod has described a series of experiments in which he employed purified animal charcoal as an antidote. Dogs, rabbits, and guinea-pigs were the animals experimented on; while the poisons consisted of large doses of opium, belladonna, aconite, nux vomica, arsenic, and other drugs. They were given without mischief when sufficient animal charcoal was administered simultaneously, or, in some instances, before the peculiar effects of the destructive drug were developed. This substance seems to act in a great measure mechanically, but it has also a power of absorbing alkaloids which may render it useful. Such substances as magnesia and gruel are sometimes given with the view of protecting the walls of the stomach, with doubtful benefit.

3. To remedy the mischief done, and obviate the tendency to death.—Unfortunately, in a great number of instances, too long an interval has elapsed between the exhibition of the poison and the time when the first-mentioned indications can be fully carried into effect; for, as before implied, if absorption has taken place, direct antidotes will be of little avail.

Our object must then be to palliate the symptoms as they arise, as well as to neutralize the effects of the poison on the constitution, by remedies of an opposite character. Thus in poisoning by depressing agents and narcotics, or such as destroy the nervous force, all lowering measures must be avoided, and agents used which will exert a contrary effect, as stimulants, cold effusion, galvanism &c. The shock to the nervous system must also be taken account, and appropriate remedies employed to aid it in rallying.

Thus direct injection of liquid ammonia into the veins has been found successful in the treatment of snake bite in Australia, by Professor Halford and others.

Claude Bernard has shown the importance of particularly attending to the way in which the poison destroys life. For example, curare paralyzes the motor nerves, puts a stop to all motion, suspends respiration, and so brings on suffocation; yet by keeping up artificial respiration for a sufficient length of time, life may be preserved till the poison is eliminated and the danger over. Strychnia attacks the sensitive portion of the nervous system; but if the external excitement, which perpetually provokes reflex action and thereby brings on fatal convulsions, be guarded against, recovery may ensue. A frog, poisoned by strychnia, rapidly dies if frequently excited; whereas left perfectly quiet under a bell-glass, it will, cÆteris paribus, recover.

Lastly, we must endeavor to promote the elimination of the poison from the body, by exciting the excreting functions; for which purpose, in poisoning by arsenic, after the stomach has been well emptied, Orfila has proposed the employment of diuretics, because it has been found that this poison, like most others, is carried off in large quantities by the urine.