Observations on the Operation and Use of Mercury in the Venereal Disease

by Andrew Duncan

Many medicines, taken into the alimentary canal, are known to have the most powerful effects in the cure of diseases very remote from thence. While this happens, there are the strongest reasons for believing, that the medicine itself never passes the alimentary canal, or is in any respect introduced into the system. In such cases, therefore, it evidently produces a good effect on parts to which it is never applied. It may then occur, as a possible supposition at least, that this likewise may be the case with mercury.

Mercury indeed produces many good effects by its action on the primæ viæ. But, when it is given in any of those forms in which it is of service in the venereal disease, those cases excepted where it is immediately applied to the diseased part itself, various phænomena tend to prove, that it actually does enter the mass of circulating fluids. It is only, from the introduction of mercury into the system, that various actions which it exerts in different parts of the body can be accounted for. Thus, for example, when it excites salivation, whether from being taken by the mouth, or from being rubbed upon the extremities most remote from the salivary glands, there is every proof which can be required that the mercury is actually present at these glands. The taste alone is sufficient to evince this. From the same mark also, we may be assured of the presence of mercury in the mouth, even when it is not introduced into the system in such a quantity as to excite salivation.

In all these cases, the mercury can only reach the mouth in the course of circulation. But, if it enter the mass of circulating fluids, it must, from the known and established laws of circulation, be equally carried to every different part of the body; and, among others, it cannot fail to be applied to those parts in which the venereal matter does exist. This first assertion, then, may be considered as sufficiently established; and, it remains only to show, that mercury, when it comes in contact with the venereal matter, has a power of destroying it.

That mercury, when it is exhibited in such a manner as to be capable of conjunction with the venereal matter, has a power of rendering it inactive, is an assertion, which, it might be imagined, could be put to the test of experiment. But, experiments of this nature could not be performed without hazard; and, in the end, would perhaps be only undecisive. Although, however, no certain criterion has in this manner been obtained, there are not wanting arguments to render the opinion at least highly probable.

In favour of the supposition, that mercury, in reality, possesses a power of rendering the venereal virus inactive, it may be observed, that an action in this manner is at least conceivable; and that it is analogous to what we have an opportunity of observing in other cases of nature. Many substances which possess the most active powers in nature, have these entirely destroyed, or totally altered, from combination with other substances. This holds remarkably of mercury itself, when united with sulphur. These, taken separately, are each of them substances of a most active nature; conjoined, the mixture becomes inert, or acts only as sulphur.

From what has been said, then, it appears, that, in some cases, mercury by combination loses its active powers. But this fact will appear less singular, if such a destruction of powers holds not of mercury alone, but of other substances likewise. That it does, is exemplified in the mixture of sulphur with different metallics, as in the case of antimony. In the mixture of acids with alcalines, there is, if not a destruction of activity, at least a total change of properties. But to multiply instances of this kind, would be superfluous. Enough has been said to show, that there is at least nothing inconsistent with the common course of nature, in supposing, that such a mutual relation takes place betwixt mercury and the venereal virus. It may then be considered at least as a possible supposition, that, from the addition of the former, the latter is destroyed, or rendered inactive.

But the proof of this antidotal power to the venereal virus in mercury, need not be rested upon a mere possibility. That mercury, in reality, does possess a power of destroying the activity of this poison, is rendered, if not certain, at least highly probable, from the circumstance of its curing venereal ulcers in consequence of topical application. In daily practice, we have undeniable proof, that mercury, topically applied, does cure venereal ulcers. This holds not only of those ulcers to which dressings can be applied, and continued for a considerable length of time, but of others also more out of reach, where its application can only be temporary. The advantages obtained from the different modes of applying mercury to ulcers in the throat, whether in the form of steam or gargle, sufficiently shew the truth of this assertion.

The cure produced in all the cases of ulcers to which mercury is topically applied, is unquestionably to be referred to an immediate action upon the part. It takes place without any marks of the mercury having entered the system. And it can by no means be alledged, that, in such cases, any general affection, such, for example, as an increased discharge, is produced. But it is perhaps needless to insist on this, as in those instances the cure is never attributed to any other mode of operation than that of immediate action. As far, then, as the assertion, that mercury cures ulcers from topical application, can prove any thing in favour of its possessing an antidotal power, it may be assumed as an undeniable fact.

It has indeed been alledged, that the cure here arising from the topical application of mercury, is entirely to be referred to its action as a stimulus to those parts to which it is applied. But this is an opinion, which, for many reasons, can by no means be admitted. Other stimuli which operate more immediately and more strongly, have by no means an equal effect. When mercury stimulates in the highest degree, the best consequences are by no means observed to arise from it. And it often produces a cure from topical application, where no effects of its operating as a stimulus can be observed. From these facts, it is evident, that the cure of venereal ulcers, produced by the topical application of mercury, can by no means be referred to its stimulant power. This naturally leads us to ascribe it to some other cause.

In the venereal disease, different parts of the body are ulcerated, and kept in that state, from the activity of the venereal poison. When, therefore, these ulcers come to be healed, the natural conclusion is, that the activity of the virus, which occasioned and supported the ulceration, is destroyed. But if mercury applied to venereal ulcers does cure them, when that cure cannot be ascribed to any action of mercury, either upon the system in general as an evacuant, or upon the part particularly affected, as a stimulant, may we not, with justice, say, that it possesses a power of destroying the activity of this virus? in other words, that mercury is an antidote to the venereal poison? From this, then, it follows, that the action of mercury as an antidote, is not merely a thing possible, and analogous to what happens in other cases of nature; but that the real existence of such a power is incontestably proved.