Medical properties and uses.-Although arsenious acid is the most virulent of the mineral poisons, yet, when properly administered, it is a medicine of great efficacy; and is employed internally as a tonic, and externally as an escharotic. It had been long used as an external empirical remedy in cancer, and internally in some cutaneous affections, both in Europe and the East Indies. It was first employed as a remedy for the cure of intermittents in Hungary; and has been long used in Lincolnshire under the name of "the ague drop;" but its effects were not clearly understood, nor the proper mode of administering it known, till Dr. Fowler of Stafford published his Observations on its use in the cure of intermittent fevers and periodical headachs.1 Since that time the authority of many respectable practitioners has been brought forward in confirmation of its efficacy in these diseases. My own experience has amply confirmed its value in lepra, chronic rheumatism, intermittent hemicrania or megrim, scirrhus; and it is stated also to have proved useful in some local painful affections "of the ends of the bones, cartilages, or ligaments, or of all three together." It has also been used in chorea, dropsy, hydrophobia, syphilis, visceral and glandular obstructions, and in many other diseases, in which, however, its efficacy is by no means established.2 In the East Indies the native physicians employ white arsenic (sanc'hya) made into pills with six parts of black pepper, for the cure of confirmed lues (Persian fire), and of a species of elephantiasis (Judham).3 It is also used in cases of the bite of the hooded snake, cobra del capello.

1 Christison on Poisons, p. 77.

2 The smelters of copper in Cornwall and Wales, although much exposed to the vapours of arsenic, yet suffer very little from them; but they are sometimes attacked with cancer in the scrotum. Dr. Paris (Pharmacologia) remarks, that they rely upon oil being an antidote; and are consequently supplied with it by their employers.

Proust, Davy, and Dr. Thomson's proportions are, arsenic 100 + 34.309 oxygen. Annals of Phil. iv. p. 176.

The internal use of arsenious acid is contra-indicated in all cases attended with strong arterial action, and where there are any pulmonary symptoms; and should a cough even intervene during its use, it should be instantly discontinued. When it is exhibited in proper cases, and with necessary precaution, the effects it produces must be carefully observed: "the feeling of swelling and stiffness of the palpebral and face, heat, soreness and itching of the tarsi, or tenderness of the mouth4," loss of appetite, thirst, want of sleep, tremors, hot skin, and quick pulse, are indications that the dose of the remedy has been carried to its full extent, and should then be diminished. If erythema or salivation appear, the use of it must be suspended; and it should be altogether abandoned, if pain of the stomach, or nausea, vomiting, headach, or vertigo be induced.

This acid is exhibited either in substance or in solution. The best mode of giving it in substance is in the form of pills, formed by rubbing one grain of the acid with a few grains of sulphur, and then beating the mixture with a sufficient quantity of crumb of bread, so as to form ten moderatelysized pills; one of which is a dose. The solution, however, is more manageable. The most common form of it is that of the London College (vide Liquor arsenicalis); but the simple solution in distilled water, in the proportion of four grains to a pint, is also given according to M. Le Febvre's method. A table-spoonful of the solution, mixed with a little syrup of poppies and half a pint of milk, is directed to be taken in the morning fasting, and the frequency of the dose increased until six spoonsful be daily taken.

1 It is a curious fact, that previous to the introduction of copper-works in Cornwall agues were very frequent; but since that period the disease is extremely-rare. "I have heard it," says Dr. Paris (Pharmacologia), "remarked by the men in the works, that the smoke kills all fevers." Is this owing to the arsenical fumes?

2 For a list of these diseases, see a paper by Mr. Hill of Chester. Edinburgh Med. Journal, v. 19. 312 and vi. 55.

3 Asiatic Researches, 8vo. 5th edit, vol ii. p. 158.

4 Dr. Kellie, Edin. Med. Journ.

As an external application, the arsenious acid has been long employed in cases of cancer; and has certainly done more to improve the ulceration, and give it a disposition to contract and heal, than any other external application. It has been sprinkled, in the form of powder, upon the sores; but the most violent pain follows this mode of applying it; and in some instances, probably from its absorption, the general system has been dangerously affected. The more usual mode of using it is in the form of a lotion, composed of eight grains of the acid, and the same quantity of subcarbonate of potassa, dissolved in four fluid ounces of water; or as an ointment, formed by rubbing together one drachm of the acid and twelve drachms of spermaceti ointment. These applications produce little pain and irritation, cause the diseased parts to slough off, and amend the fetid discharge; but although to a certain extent they produce the most beneficial effects, yet the instances in which a cure has been effected are very rare; and they sometimes convey into the habit enough of the acid to produce much mischief.

Arsenious acid is not unfrequently the cause of death, from accidents occurring to those artists who use it in their manipulations; as glass-makers, dyers, and workers in gold; or from ignorance of the proper dose of its preparations when medicinally used; or from the employment of it as a poison. The symptoms which occur are either those of inflammation of the stomach, incessant vomiting, purging, a sensation of heat, and pain of the stomach1; constriction of the throat, an increased flow of saliva, and great heat of the mouth; rapid sinking of the pulse, which is at first full, hard, and frequent, cold sweats, convulsions, and death; or if the quantity be not sufficient to produce speedy dissolution, the principal operation of the poison is on the vascular and nervous systems. The first-mentioned symptoms are often absent, or are succeeded by paralysis, hectic, syncope, and other symptoms of extreme debility.1 When death takes place, symptoms of putridity are said soon to present themselves; but this is not always the case, although the body is often marked with livid stripes, and covered with ecchymoses; and on dissection, the stomach often, although not always, is found to be either abraded, or completely eroded in several parts; with appearances of inflammation extending through the whole abdominal viscera; often extravasation of blood into the cellular tissue of the canal, ulceration, softening of the mucous tunic, and occasionally gangrene.