Active Ingredients. - Camphor, when extracted and purified, is white, concrete, crystalline, semi translucent, somewhat granular, tough, and difficult to pulverize. The odor is strong, penetrating, and characteristic; the taste is pungent, bitter, and aromatic. It is lighter than water, the sp. gr. being 0.98; at ordinary temperatures it is solid, but, owing to its volatility, slowly evaporates. Under the influence of heat it rapidly and entirely sublimes; it melts at 288°, and boils at 399°, and when ignited burns with a bright flame and copious production of smoke. In water it is very sparingly soluble, so that if water be added to the alcoholic solution, which is readily made, the camphor immediately precipitates. It is soluble also in ether, and in the volatile and fixed oils. The characters of camphor are thus pretty much those of a concrete volatile oil. By constant heating with nitric acid it becomes oxidized, and converted into camphoric acid.

Physiological Action. - It is singular how little is yet known with accuracy on this point, notwithstanding the large number of strong statements that have been made by various writers respecting the action of camphor.

It is certainly known, however, that camphor will, in very large doses, cause death, preceded by delirium, coma, and convulsions. There are certain concentrated spirituous preparations of camphor, originally intended to be taken in very small quantities, which the folly of patients not unfrequently induces them to prescribe for themselves in large quantities: in this way many serious consequences have occurred. In man lam not aware of camphor having proved fatal except in one case. But there are numerous instances upon record in which it placed the recipients in imminent danger; and one of the earliest cases that were recorded with exactness still remains as instructive as any, viz., that of Mr. Alexander.1 That gentleman took forty grains of camphor, mixed with syrup of roses, for experimental purposes. In twenty minutes he was languid and listless; in an hour he became giddy, confused, and forgetful. All objects quivered before his eyes, and a tumult of undigested ideas floated through his mind. At length he passed into total unconsciousness, and in that state was attacked with strong convulsions and maniacal frenzy. The nature of the accident having been suspected, an emetic was given, with the effect of expelling almost the whole dose of camphor that had been swallowed. The graver symptoms then disappeared, but a variety of singular mental affections continued for some time. Considering how small a proportion of the camphor had been dissolved at the time when the emetic was so happily administered, one cannot doubt that much less than the forty grains, if fully taken into the blood, would have proved fatal to this particular person. There is no doubt, however, that much larger doses than this have been taken without inducing more than temporary and not very severe effects. How much of this variability of effect is really due to idiosyncrasy, and how much to mere difference in the rate of absorption must, however, remain at present undecided.

Upon animals many persons have experimented with large and fatal doses, and the post-mortem appearances have proved that, besides its

1 Quoted in "Christison on Poisons." action upon the nervous centres, camphor has the power of a direct irritant to the alimentary canal, and also to the mucous tract of the genitourinary organs.

One of the phenomena which have been often, though not always, noted in severe camphor-poisoning, is dilatation of the superficial vessels, especially of the head and face; this is usually accompanied by delirium.

Upon the skin camphor is well known to act as an irritant. A concentrated solution rubbed in soon causes heat and bright redness; and if it be applied to a raw surface there are intolerable burning and consecutive inflammation.

The recent researches of Grisar (upon valerian oil and other ethereal oils) also included experiments with camphor, and it was found that in certain doses camphor decidedly exhibits a power of reducing exalted reflex irritability. It is not improbable that to this function we must attribute its distinct, though not well understood, capacity of subduing certain forms of diarrhoea.

On the whole, while our knowledge of the physiological action of camphor must be allowed to be at present very partial and confused, it is probable that Nothnagel is right in his statement that the apparently conflicting attributes of sedation and stimulation which have been ascribed to this drug are both correct; the difference being in fact a matter of dose and occasion.

Therapeutic Action. - There are at least two ways in which camphor often proves distinctly beneficial.

1. As a remedy for Functional Nervous disorders not of the severest type, it is often efficacious. In that type of nervous headache which, without attaining the character of well-marked rhythmical migraine, very closely borders upon it as regards the character of the pain, and is most commonly seen in hysterical females, camphor is very useful. From three to five grains of camphor rubbed down with a little spirit, and suspended in water by the aid of some tragacanth, and a twenty- or thirty-grain dose of carbonate of magnesia, is an excellent though apparently rather clumsy form. The magnesia is not superfluous, for it often assists the cure by correcting gastric acidity which is present at the time.

In Hysteric Excitement, and also in Chorea, when these are not of the graver types, camphor is often of considerable use; and it has even been seen by Van der Kolk to prove useful in a case of acute mania in which other very powerful remedies had failed. In Delirium tremens and in spasmodic Asthma it has also been strongly recommended by various authors. But with regard to all these maladies the same remark must be made about camphor as was made by Van der Kolk respecting its use in insanity, viz., that its effects are widely different in different individuals, and that we never can tell beforehand whether it will act well or not.

2. In many forms of Diarrhoea camphor proves extremely useful, and it is of much importance to define accurately the cases in which it may be expected to prove efficacious. They are evidently those in the production of which nervous irritation has a large share. Among the cases of diarrhoea that occur in high summer heat, there are many distinguished by clear red tongue, in which the mingled exhaustion and irritation of the nervous system are for the most part the true sources of the flux, and here camphor will do very much good; indeed, a few doses of three or four grains or drops will often completely check the disorder.

Camphor is less useful in proportion as the diarrhoea is more dependent on local irritation from unwholesome food, etc. And as to the assertions that have been made with regard to the power of this drug to arrest Asiatic cholera, I have never witnessed such effects, except in the first (or doubtful) stage, and I cannot but suppose that some error in diagnosis has been made in most instances of supposed cure.

If we carefully consider all the best ascertained therapeutic effects of camphor, there appears a high probability that the secret of its beneficial action under very varying superficial conditions depends upon the power to subdue reflex excitability, which is indicated in the experiments of Grisar made with it and with valerian oil, etc. It is difficult otherwise to explain its ancient high reputation as an anaphrodisiac, and the strong modern recommendations of it in all kinds of irritable conditions of the external and internal sexual organs. No one who tries it in an unprejudiced manner can help observing that it fails quite as often as it succeeds in any one of these disorders, and in fact it is impossible to discern any proof of a direct action either upon the sexual organs or upon the nervous centres that govern them, except so far as a general state of exalted reflex irritability may exist, and may be calmed by the remedy. It is even probable also that a large portion of the so-called stimulant effects for which it has been so warmly praised by Copland and others in the treatment of adynamic fevers, etc., is really only a tranquillization of the reflex apparatus which can be obtained with less of general depression than would be likely to follow the use of other narcotics.

As an External remedy for pains, camphor is a good deal employed in the form of liniment, and is generally credited with good effects, but its action is very uncertain.

Finally, some persons recommend its use as a diaphoretic. It has been already mentioned that in many cases of camphor-poisoning an immense dilatation of the superficial blood-vessels has occurred. This dilatation of peripheral vessels, attended by copious sweat, can be produced by the use of camphor vapor, from the heating of camphor on a plate over which the patient sits with a blanket pinned around his neck, so that the fumes do not enter the throat.

Preparations and Dose. - Camphora, gr. iij. - x. (.20 - .65);

Oleum Camphorae, m j. - iij. (.05 - .15); Aqua Camphorae, 3 ij. -

Camphor Camphora Officinarum 47

(8. - 3.); Spts. Uamph., m x. - 3 j. (.65 - 4.); .Linimentum Camptiorae.