SILVER, Medical Properties of. In a purely metallic state silver has no action on the animal frame, and the only salt much used is the nitrate, termed also lunar caustic. This is always fused in proper moulds, from which it is turnedf out in the form of cylinders, about three inches long, and the eighth of an inch in diameter. They are at first white, but quickly become of a dark gray or black colour, from combining with organic matter in the air. To prevent this the cylin ders are generally wrapped up in blue paper. When nitrate of silver is brought in contact with any part of the human frame, it causes first a white mark, which gradually changes to blue, purple, and at last to black. This occurs more rapidly if moisture be present; and is owing to a chemical combination of the metal with the albumen and fibrin of the animal tissues. If the part be wetted, and the caustic applied several times at short intervals, vesication results. Nitrate of silver acts therefore locally as an irritant and corrosirc. When taken inter. nally in small doses for n considerable time, such AS six or twelve months, it is absorbed and deposited in various parts of the body, and when it is deposited in the rote mucosum of the akin it causes dia. colorations, which in most cases prove permanent. It has been some. times employed with success in the treatment of epilepsy, chorea, and some forms of angina pectoris, as well as morbid sensibility of the stomach. Larger doses can bo borne when it is administered in the form of pill than in solutiou. The pills should be made with mucilage and sugar, but not with bread-crumb, as the common salt, or chloride of sodium, decomposes the nitrate and renders it inert. In cases of poisoning by nitrate of silver, common salt is a ready and effectual remedy : also milk. The liability of nitrate of silver to produce discolomtions of the skin in persons taking it internally constitutes a serious objection to its employment, and there appears little necessity for giving it, since any case of epilepsy likely to be benefited by it will generally receive equal good from the use of oxide of zinc, without the risk of stains or other inconvenience.
The external employment of this agent is not liable to any objection when used cautiously, while its advantages are very great. It is the most powerful direct antiphlogistic agent known. All subacute inflam mations in any part to which it can be immediately applied will subside under its influence. In inflammations not merely of the
skin, but of mucous membranes when they occur in parts which are accessible, its influence is great and speedily manifested. Many of the cases of croup which in an advanced stage are unmanageable, begin in the back part of the throat (lances), and if these parts are freely touched with a pencil dipped in a strong solution of nitrate of silver, the farther downward progress of the inflammation may be arrested. Similar benefit attends its use in diphtheria : for this a very strong solu tion in nitric ether is best. The same treatment is applicable to the erythematous inflammation which frequently begins either externally, and spreads through the mouth or nose to the latices, and thence down the or originates in the lances, leading to very serious results. Erysipelatous inflammation occurring in any part of the body may be effectually limited by nitrate of silver. For this purpose a complete circle should be formed round the inflamed part, but on the sound skin. For this case the solid cylinder, moistened at the end, is best. The circle must be perfect, or the morbid action may extend, escaping at the smallest breach. Chronic inflammation, and even ulceration, of the eyes, may be removed by nitrate of silver applied in different forme. Old indolent ulcers are stimulated to a healthy action by its use; and many cutaneous diseases removed by it. Recent burns have the severe pain often very much mitigated by it; but it must not in any of these cases be applied to too large a surface at once, as ill effects have followed such a practice. To specify all the uses of nitrate of silver would be impossible here, but one more deserves to be extensively known. It is the best application to chilblains, especially at first ; but even after they break, it disposes them to heal.
When a solution of nitrate of silver is made, distilled water should invariably be used. The neglect of tide rule causes many of the solu tions applied to the eye to be not only useless, but hurtful. Oxide of silver has been strongly recommended as an antispasmodic, and not liable to the objections which attach to the nitrate. In preparing medicines with oxide of silver, care must be taken not to combine it with articles such as ammonia, lest an explosive compound should result.