ARSENIOUS ACID.

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required: but, besides the danger of causing constitutional symptoms,to which all arsenical compounds are liable, it is apt to occasion ery-sipelas.

Arsenious acid, or sesquisulphuret of arsenicum, is a constituent ofmost of the preparations sold as depilatories; as Delcroix's Poudre Subtile,which, according to Dr. Paris, consists of quicklime, sulpliuret ofarsenic, and some vegetable powder. Such applications are exceedinglydangerous.

Administration. —Arsenious acid may be administered, in substance,in doses of from one-sixteenth to one-eighth of a grain, made into pills,with crumb of bread. In making a mass of pills, great care should betaken that the arsenic be equally divided; for this purpose it should hewell rubbed in a mortar with some fine powder (as sugar) before adding! the bread crumb. A much safer mode of exhibition is to give thisj potent remedy, in the form of solution, with potash (as the liquor potasses\ arsenitis). But I have already mentioned, that Dr. Macculloch foundi solid arsenic more efficacious than this solution : and Dr. Physick, of theUnited States , thinks “ that they act differently, and cannot be substituted! for one another” {United States Dispensatory). Whether given in the| solid or liquid form, it is best to exhibit it immediately after a meal,

J when the stomach is filled with food; for when given on an empty sto-| macli (as in the morning fasting), it is much more apt to occasion gastricI disorder. It is sometimes advisable to conjoin opium, either to enablethe stomach to retain it, or to check purging. In debilitated constitu-tions, tonics may be usefully combined with it. An emetic (as ipeca-cuanha), or a laxative (as rhubarb), may be employed where the stomachis overloaded, or the bowels confined. Its effects arc to be carefullywatched, and whenever any unpleasant symptoms (as vomiting, griping,purging, swelling or redness of the eyelids, dryness of throat, ptyalism,headache, or tremors) make their appearance, it will of course be advisableto diminish the dose, or suspend for a few days the use of the remedy.Indeed, when none of these symptoms occur, it is not proper to continueits use more than two weeks without intermitting its employment for aday or two, in order to guard against the occasional ill consequencesresulting from the accumulation of the poison in the system.

1. Liquor Potjssje Arsenitis, Ph.Lon. &U. S.; solutio arsenicalis,Pli. Ed.; Fowler's or the mineral solution (arsenious acid, carbonate ofpotash, aa gr.lxxx.; compound tincture of lavender, 5v.; water, 5xx.) Thearsenious acid and carbonate of potash are to be boiled, with the water,in a glass vessel: arsenite of potash is formed, and carbonic acid evolved;but the quantity of carbonate of potash is not sufficient to saturate theacid. The compound tincture of lavender, which is used as a colouringand flavouring ingredient, is to be added to the solution when cold, andafterwards more distilled water,to make the whole amount exactly to a pint;(i, e. twenty ounces). The dose of this solution is four or five minims,gradually and cautiously increased. I have known 15 minims takenthree times a day for a week, without any ill effects. Dr. Mitchell, ofOhio , has given from 15 to 20 drops, three times a day, in intermittents(United States Dispensatory). But as some persons are peculiarly sus-ceptible of the influence of arsenic, we ought always to commence withsmall doses. It has been given to children, and even pregnant women.Dr. Dcwees {Philadelphia Journ. of Med. <k Phys. Sc. xiv. 187) adminis-