ARSENIC A very soft, brittle, and eminently poisonous metal, of a steel gray color : its sp. gr. 5.7. It volatilizes, exhaling a strong odor of garlic, before it fuses, at a temperature of 365° F., and is easily inflammable. It combines with oxygen in two proportions ; and as both compounds are sour, and form salts with bases, they have been termed arsenious and arsenic acids : the former is com posed of 38 arsenic and 12 oxygen, and the latter of 38 arsenic and 20 oxygen. Ar senious acid is more commonly known under the name of white arsenic, and is the usual state in which this poison oc curs in commerce ; it is obtained during the extraction of several of the metals from their ores, and is a white, brittle, semi-transparent substance, having little taste, but is virulently poisonous. Its sp. or. is 3.7. It forms a dull white powder, and it is in this form that it is usually sold. When heated in the flame of a candle, it rises in the form of a white poisonous vapor, and exhales, in consequence of its partial reduction, a strong garlicky smell: 1000 parts of cold water dissolve about 21 of white arse nic; but when the water is boiled with the arsenic, 1000 parts take up between 77 and 78 ; and this solution, after stand ing a few days, deposits rather more than half of the white arsenic, in the form of small crystals, retaining about 30 grains in permanent solution. White arsenic dissolves in the alkalies, and com bines with the metallic oxides, forming a class of salts called arsenites : they are all poisonous. Of these the arsenite of potash is used in medicine, under the name of Fowler's mineral solution : it is employed in very small doses in the cure of agues, and is an effective remedy, but requires much care in its administration.
When white arsenic is taken as a poi son,—that is, in large doses, it produces violent spasmodic pains of the stomach and bowels, attended by a sense of beat, and constriction in the mouth and throat; an increased flow of saliva, tightness about the head, itching of the face and neck, and nausea. These symptoms are succeeded by vomiting and purging and excruciating pains ; the pulse at first full, hard, and frequent, sinks and becomes irregularly feeble, and clamminess of the skin, cold sweats, purple spots, and con vulsions, precede death ; or if the pa tient escape this catastrophe, it often happens that hectic fever, paralysis, and mental and bodily debility, attend him for the remainder of his days. It is often said that the bodies of persons poisoned by arsenic are very prone to putrefaction ; but this does not appear to be always the case. After death the stomach and bowels are usually found inflamed, but often only slightly so ; and it appears from Sir B. Brodie's observa tions, that this poison kills by some pe culiar action upon the heart and nervous system. The treatment of persons thus poisoned consists in promoting the vo muting by an emetic, composed of a so lution of 20 grains of sulphate of zinc in two ounces of water, aided by copious draughts of warm barley-water or gruel ; but the most effective means of getting rid of the arsenic, is by the use of the stomach-pump, which, when immediately resorted to, has often saved the patient.
The after-treatment requires much cir cumspection.
The only ready means of ascertaining the presence of white arsenic is by heat ing the suspected substance upon a red hot coal, or in the flame of a candle or spirit lamp, when it will exhale the pe culiar arsenical odor resembling that of garlic ; but the treatment of persons poi soned by arsenic, and its detection in doubtful cases, must be left to the medi cal man and the chemist. It is impossi ble too strongly to represent the evil which results from the unfettered sale of arsenic, and from the unwarrantable use of it as a poison for rats, and as a veteri nary remedy, for it is thus that it finds its way into culinary vessels, gets acci dentally mixed with articles of food, and that bottles which have contained it are used for beer, wine, vinegar, or medi cine : its sale shouM be rigidly prohibited. This metal occurs native in the state of white oxide (arsenious acid); also with sulphur I known as yellow and red ar senic. t is associated with a great many metallic ores, but chiefly with cobalt in Silesia, in Europe. It is separated from that metal by roasting, and the arsenic is obtained as white oxide. Arsenic enters into the composition of flint glass, the body of which it whitens and purifies: it is apt, however, to make the glass milky. It is used in candle-making, to remove the crystalline tendency of stea rine. It is also used to destroy rats and vermin. It has a remarkable tendency to preserve the parts of the animal body it is brought into contact with, and hence it has been used in the stuffing of birds and the preservation of other objects of natural history. To make an appropriate preparation Dumas gives the following recipe : White soap and arsenious acid, of each 100 parts ; carbonate of potash, 30 parts ; camphor, 15 parts ; quicklime, 12 parts. The potash, soap, and lime, are melted together then the arsenic is added. The camphor is dissolved in alcohol, and added in when the mass is cold. Some of this soap mixed with water is laid on with a brush. Arsenic alloyed with me tals makes them more brittle and fusi ble : with copper it forms white tombac.
Arsenic acid is more soluble and sour, but equally poisonous with the arsenious acid. Its salts are called arsenates, and the arseniate of potash obtained by de liagrating a mixture of white arsenic and nitrate of potash is occasionally used in medicine : it is the active ingredient in the tasteless ague drop. It is also used in calico-printing as a resist paste laid on by blocks to prevent the mordant acting on the cloth in those places.