Antimony forms two classes of salts, antimonious and anti-monic. In the former it is tri- and in the latter pent-atomic.

General Sources. - It is chiefly found native in the form of the black antimonious sulphide, Sb2S3.

General Reactions. - It is recognised by the orange-coloured precipitate which it gives with sulphuretted hydrogen in acid solutions. A characteristic reaction is the white precipitate

Which falls on throwing a strong soultion of a salt of antomony, such as the chloride, into water, and the change of the white into an orange colour on the addition of sulphuretted hydrogen. A similar reaction occurs with salts of bismuth, but the white precipitate becomes black on the addition of sulphuretted hydrogen (p. 713).

A solution of chloride of antimony gives with potash or soda a white precipitate which only dissolves in large excess, and with ammonia a white precipitate insoluble in excess. But if tartaric acid be present the precipitate dissolves in a slight excess of potash or soda, and with ammonia only a slight precipitate is formed.

1 It contained 1 in 109 in B.P. 1867. The original Donovan's Solution contained nearly 42 grains of each iodide in 10 fluid ounces.

General Actions of Antimony. - Salts of antimony probably combine with albumen, but in alkaline solutions they form no precipitate. They only form precipitates in acid solutions, and they consequently appear to exert an irritant action only on those parts of the animal body where they meet with an acid secretion, such as the orifices of the sweat-glands and of the stomach. When applied to the skin the chloride of antimony destroys the cuticle, and acts as a powerful escharotic, producing a deep slough and a slowly healing sore.

The other preparations, however, instead of affecting the whole surface to which they are applied, produce inflammation in isolated spots, which, beginning with papules, proceeds to pustules resembling those of small-pox. A similar pustular irritation is sometimes noticed upon the fauces of persons who have been taking antimony for some time, or have been poisoned by it. When taken internally, small doses produce little more than a feeling of warmth in the stomach and slightly increased diaphoresis, but larger doses cause loss of appetite, nausea accompanied by enfeeblement of the circulation, and a feeling of great depression and weakness. Not only the secretion of sweat, but those of the mucous membranes, stomach, intestine, and respiratory passages, seem at the same time to be considerably increased. In still larger doses antimony produces vomiting, with great depression of the circulation, and relaxation both of the voluntary and involuntary muscles. In large and poisonous doses it causes gastro-enteritis, with profuse diarrhoea and extreme collapse. The pulse is small and quick, the surface cold, and covered with clammy perspiration. There is great weakness and severe cramps of the extremities, and the symptoms somewhat resemble those of Asiatic cholera. Death may occur in this condition. It is sometimes preceded by delirium and convulsions, and tonic or clonic convulsive spasnis.

The treatment of antimonial poisoning consists in the administration of tannin, and in some readily accessible form. The most easily obtained is a strong infusion of tea, and the tannin is more readily extracted from this by the addition of a small quantity of bicarbonate of sodium. Infusions of oak bark or of cinchona may also be used if obtainable. Milk and mucilaginous drinks may also be used. A diffusible stimulant should be given to counteract the collapse.

The mode in which tartar emetic causes vomiting has given rise to considerable dispute. It acts as an emetic even when injected into the veins, as well as when given by the stomach, and it was found by Magendie that when the stomach of an animal was excised, and a pig's bladder filled with liquid attached to the lower end of the oesophagus, the injection of tartar emetic into the circulation caused movements of vomiting, and the contents of the bladder were expelled just as if the stomach had been in situ. This experiment seemed to prove not only that the act of vomiting was independent of the movements of the stomach itself, but also that tartar emetic caused vomiting by acting upon the vomiting centre, and not upon the stomach. The objection, however, has been raised that the action of the drug upon the vomiting centre is not direct, but reflex; and it has been urged that, although the stomach was removed, the antimony might still be carried by the circulation to the oesophagus and intestines, and by there causing irritation might produce reflex vomiting. This seems improbable, especially as the antimonial salts have a comparatively slight action on organs having, like the oesophagus and intestines, an alkaline reaction, instead of an acid one, as the stomach has.

It is probable, then, that tartar emetic does produce vomiting by its direct action on the vomiting centre in the medulla oblongata, but this direct action is not the only way in which it stimulates the vomiting centre - it also produces a reflex action upon it through the stomach. For it has been found that even when tartar emetic is injected into the veins, it is eliminated by the mucous membrane of the stomach (p. 38 et seq.), and may thus act upon that organ in the same way as when introduced directly into it. If its emetic action be due in any great measure to irritation of the stomach, one would expect that a smaller dose would be found sufficient to produce vomiting, when introduced directly into the stomach, than when injected into the veins, for in the former case the whole of it will come in contact with the stomach and will do so at once; in the latter case only a fraction of the quantity injected into the veins will reach the stomach, and some time will be required before it accumulates in the gastric mucous membrane sufficiently to cause irritation. This is exactly what is found by experiment, and vomiting is produced more quickly, and by a smaller dose, when the drug is introduced into the stomach, than when injected into the veins, just as we should expect to be the case if its emetic action were due in considerable measure to its action upon the stomach itself. This view is also supported by another experiment, for after the nervous channel by which impressions are conducted from the stomach to the vomiting centre is destroyed by section of the vagi, double the dose of the drug is required in order to produce vomiting. It may then be concluded that antimony acts chiefly as an emetic by irritating the stomach, and thus exciting the vomiting centre reflexly, but that it also acts directly on this centre when conveyed to it by the blood (p. 373).