i shall treat first of the effects and uses of arsenic as a medicine, and then of its several preparations. it will be understood that, in the following observations, it is not the metal in its uncombined state that will be under consideration, but those states of it, whatever they may be, in which it actually operates on the system. There can be no doubt that it is the arsenic itself which gives to all its preparations whatever peculiar efficiency they may possess, although, when quite pure, it may have but a very doubtful influence.

Arsenic has by some been ranked among the tonics; but it has always appeared to me, judging from its known effects, to be very different in its operation from those medicines, considered as a class. The antiperiodic power which it possesses in common with Peruvian bark and its derivatives, and which has mainly led to this opinion of its character, is not specially a tonic property, and does not belong to bark itself as a tonic. The medicine which probably possesses it in the highest degree, next to the two mentioned, is opium, which certainly has no claim to be ranked with the tonics. The effects of arsenic are quite peculiar, and, in the existing state of our knowledge, it is impossible to place it in any other association of medicines than the present, without leading to false notions of its character.*

* it is right to say that this view of the remedial properties of arsenic is not universally accepted. By M. A. Wahu, who has written on the subject, it is considered as the best reconstructive medicine in our possession. This character is manifested, 1. in the increased appetite, the correction of constipation without the production of diarrhoea, and the general regularity of the digestive processes; 2. in the improvement of the function of respiration in its relation to the blood; 3. in the greater muscular vigour; and 4. in the favourable influence of the improved health upon the mental condition. Hence its peculiar efficacy in the cachectic state of malarial fevers, and that which is so apt to follow these fevers; in the condition of system predisposing to phthisis; in the anemic condition; and in the feebleness of old age. (Ann. de Thérap.,

1. Effects On The System

In its lowest remedial doses, arsenic may often be given for a considerable time, without any other discoverable sign of its operation than the relief or cure of the disease for which it may be administered. it is, therefore, properly an alterative. Generally speaking, however, it does produce some observable effects, which serve as a signal to the pre-scriber to diminish the dose, or to withhold the medicine for a time. The symptom which I have generally noticed among the first, when it is very carefully given with a special view to avoid gastric irritation, is an edematous state of the eyelids and the cellular tissue of the face beneath them. if the medicine be persevered in, this oedema may spread considerably; and it is so common an effect as to have received the name of oedema arsenicale. I have met with one instance, and only one, in which this effusion appeared to extend over the body, constituting a full attack of anasarca; and in that case, which was one of intermittent fever in a boy, I was unable to determine, certainly, whether the dropsy resulted from the arsenic or from the disease, though inclined to ascribe it to the former. The oedema does not, in general, make its appearance until some days after beginning with the medicine, sometimes not for a week or ten days, or even more; and I have earned patients through a course of treatment extending to months, with the effect of curing long-continued skin affections, without any symptom of the kind, or indeed any other disagreeable symptom.

If, however, the dose is somewhat large, or the patient peculiarly susceptible, the first sign of the action of the medicine is usually presented in the stomach. Sometimes there is a slight temporary increase of appetite, such as any acrid substance may produce by its first excitant impression; but more frequently the patient complains of heat in the throat, epigastric uneasiness, anorexia, nausea, or burning pain in the stomach, and sometimes of general heat, and more or less headache, while the pulse is somewhat accelerated; symptoms, however, which subside quickly on the omission of the medicine. Should it be persevered with, or given still more largely, the irritation of the primae vise is greatly increased; vomiting and purging, with griping pains ensue; and other symptoms which indicate derangement of the system at large, such as heat and dryness of skin, excited pulse, languor, weakness, wakefulness, etc. Beyond these, the effects of arsenic cannot proceed without becoming poisonous; and, as soon as the symptoms appear, the medicine should be at once omitted.

1866, p. 256.) The reader need not be informed that these opinions about the physiological properties and therapeutical effects of arsenic are not those of the author. I have prescribed arsenic very frequently both in public and private practice, and have had occasion to use it in my own person in reference to its curative influence; but have met with none of the remarkable effects as a tonic, above enumerated, except sometimes, perhaps, the provocation of an appetite, as the slightest result of its irritative property; and, as regards its medical use, the conditions of system in which M. Wahu has found it most efficacious are those to which I think it least applicable, and which, indeed, are very apt to result from its abuse. So far, therefore, as my own experience and observation can be allowed weight, I would guard the young practitioner against being led astray by these notions of arsenic as a reconstructive agent. indeed, it is only when it produces no sensible unpleasant effect that M. Wahu claims for it these powers; and there is here ample play for the influence of the imagination and of preconception. (Note to the third edition.)