2. As a Caustic, Alterative, etc., jointly. The number of affections in which nitrate of silver is employed, with these complex objects, is very large. They are, however, generally ulcerous in their character. When the caustic is applied over the whole of an ulcerated surface, it produces a white crust, which, if the ulcer is small, gradually darkens, hardens, and contracts, forming a sort of scab to the diseased surface, which heals under its protecting influence, and, when it falls off, has generally become covered with a new cuticle. When this does not happen, ulcerated surfaces, whether specific, as in syphilis, or simply obstinate through habit, indolence, or debility, are often rapidly benefited by successive applications of this agent, and speedily get well after long fruitless efforts with other means. The remedy operates, in these cases, on several different principles.

In the first place, through its caustic operation, it removes portions of the diseased surface, and often probably the whole of that in which any special or specific morbid action resides, leaving, after the separation of the superficial slough, only a healthy ulceration, disposed, like that of a recent wound, to heal. Perhaps, even in many simply indolent ulcers, it is only a slight depth of tissue in which the feebleness and indolence reside. The caustic operation, moreover, proves useful in removing the callous edges of ulcers, which, wholly incapable of due action themselves, serve as foreign bodies to prevent healing, and keep up irritation in the parts beneath them. Such a surface, of almost cartilaginous character, sometimes lines old fistulous sores, and is wholly incompatible with the healing process.

Secondly, the salt operates by its excitant property, which rouses debilitated surfaces to healthy activity, and often proves useful, even though no escharotic effect has been produced.

Thirdly, the astringent action of the nitrate must often prove serviceable III relaxed, flabby, and fungous ulcers.

Fourthly, we may say of this remedy, as of many others, that it is capable of exercising an alterative or substitutive influence upon diseased structure, either directly changing the nature of the existing action into a healthy one, or replacing it by a more energetic operation of its own, which, ceasing after a time, leaves the parts in a normal condition, and therefore disposed to heal.

Fifthly, I believe that there is yet another, and probably still more efficient agency, by which the curative effects in these cases are produced. I mean a protective influence, by which, through the impenetrable coating which the escharotic gives to the diseased surface, it protects it against the injurious influence of atmospheric air, and other causes of irritation from without. I shall have occasion to treat more fully of this agency under the class of medicines which I designate as Protectives, when I hope to show that this is a highly important therapeutic influence, susceptible of extensive application in the cure of inflammatory and irritative diseases.

By one or more, or all of the above modes of action, nitrate of silver is rendered, probably beyond all other agents, effective in the cure of ulcers.

It is unnecessary to treat of the several forms of ulceration in which it is used with advantage. it may be tried, as a general rule, with good hope of cure, in all which refuse to heal under mild applications, and which are not sustained by some constitutional disorder, or inherent vice of their nature, as cancerous ulcers, for example. Even in the latter classes, it may still be employed as a palliative, and in some cases, though it will not remove the constitutional affection, may cure the existing local disease.

Among the ulcers to which the remedy is peculiarly applicable, may be mentioned the primary syphilitic chancre, obstinate ulcers in the mouth and fauces, gangraena oris, scrofulous ulcers of the cornea and conjunctiva, lupus, and generally all chronic, indolent, or flabby ulcers, with callous edges, fungous growths, etc. Even inflamed or irritable ulcers will often yield to this remedy duly applied; and this leads us to another application of nitrate of silver, perhaps not less important than that just noticed.

3. As an Antiphlogistic Agent. Upon the same protective principle above alluded to, nitrate of silver operates powerfully as an antiphlogistic remedy. it is to Mr. Higginbottom that is mainly due the great extension given to this application of the remedy. in all kinds of superficial inflammation, whether of the mucous membranes or the skin, whether acute or chronic, whether of the ordinary character or specific, if nitrate of silver can be brought to bear with full force upon the diseased part, some favourable influence may be hoped for, and very frequently a cure effected. Even when the inflammation is seated beneath the two issues referred to, but without the great cavities, more or less of an antiphlogistic effect is often exerted. Though, as I believe, the result is mainly dependent on the protective principle, there are probably other modes in which the remedy operates. Sometimes it may act beneficially as an astringent, causing the congested vessels to contract, and thus diminishing the supply of blood. in the advanced stages, it may operate advantageously not only in this way, but also by a simple excitant effect upon the enfeebled and relaxed tissue. Again, it probably acts in some cases as an alterative or supersedent remedy, especially in those inflammations which are of a specific character.

But, though thus generally effective, the remedy will not always succeed, and, if it fail, may sometimes do harm by its excitant influence in acute cases. When the local affection is the result of the general state of the system, when it is complicated with fever and plethora, and especially in the highest state of inflammatory excitement, nitrate of silver will often fail. Nor, as a general rule, should it be applied under these circumstances. The cases to which it is best adapted are superficial chronic inflammation in general, acute inflammation of the diphtheritic or pseudomembranous character, and the declining stage or suppurative condition in other cases, when nature seems inadequate to a cure. Sometimes, also, it proves effectual in the very forming stage of ordinary inflammation, while the disease is yet mainly in the congestive state.