But, to prove that evacuation will not cure the distemper, it is needless to travel back to the first periods of this disease, or to rest the evidence even upon the highest probability. From what occurs in many morbid cases, we have every day evident proof of the insufficiency of any discharge for producing a cure of the venereal disease. Lues venerea often exists at the same time with diseases in which an increase of natural evacuations takes place. None of these diseases, whether the evacuation happens by the salivary glands, as in small-pox, by stool, as in dysentery, or by the skin, as in intermittents, have ever been found to break its force, much less to produce a perfect cure.
Besides what happens in natural evacuations, we have likewise proofs of the insufficiency of artificial evacuations for the cure of this disease. Although evacuation, at least by other means than by the use of mercury, is never now employed as a cure for the venereal disease; yet venereal complaints are often complicated with others, for which various evacuations are proper. And while evacuations are, with success, employed for the cure of these, it is found, that the venereal taint either remains unchanged, or is even increased in force. It cannot here be alledged, that the difference of effect depends upon the mode of evacuation. On such occasions, every mode of evacuation has been tried with equal want of success. Even salivation, which was long considered as the only effectual discharge, when excited by other means than by mercury, or even by mercury itself, when externally applied to the organs secreting saliva, has not been found more effectual than other modes of evacuation. In some cases, indeed, mercury received into the mouth by steam, or otherwise, has had good effects; but these were either to be accounted for from its application to the diseased part, or from its introduction into the system. It is, then, sufficiently evident, that evacuation, at least by other means than mercury, does not cure lues venerea.
To this theory it may be urged as a third, and not less powerful objection than any of the former, that where the evacuation arising from the use of mercury in lues venerea is the greatest, the cure is often retarded; and that mercury never more frequently fails than in those cases where it begins to evacuate upon its first introduction into the system.
That these assertions are true, at least of the obvious discharge produced by mercury, will not be refused by any advocate for its action as an evacuant. To this, indeed, they may think it a satisfactory answer, that the influence of mercury as an evacuant cannot be judged of from the apparent discharge. It may be alledged, and indeed with some appearance of reason, that the greatest discharge produced by mercury is by insensible perspiration; that mercury, in consequence of this, is a more powerful evacuant than many other medicines by which a greater obvious evacuation is produced; and that it has the effect to increase perspiration in a more remarkable degree, when it increases no other discharge than when it induces the greatest obvious evacuation. But although it cannot be denied, that the use of mercury does increase insensible perspiration; and that evacuation in this way may, on some occasions, be greater than what would arise from salivation or any other obvious discharge; yet these facts by no means tend to any conclusion which will remove the difficulty formerly stated. Nor can it from thence be supposed, that mercury always evacuates most powerfully in those cases where it produces the most successful cure.
The degree of evacuation which takes place from the employment of any medicine cannot indeed, in every case, be ascertained by the obvious discharge. But, where the judgment formed from this test would be fallacious, the marks of inanition consequent upon the use of any medicine are always certain tests for determining the degree of evacuation. From these it is evident, that the suppositions here advanced, that mercury operates more powerfully as an evacuant than any other medicine, and that it always produces a greater discharge when it acts by the skin, than when it affects the salivary glands, or any other excretory, are entirely without foundation.
From the marks of inanition appearing in the system, it is demonstratively proved, that, from a variety of other means, a greater evacuation can be produced than from mercury. In such circumstances, however, by mercury the venereal disease is cured, by these other evacuants it is not. And farther, where the cure of lues venerea has been retarded by a salivation occurring early, or where no cure has taken place after salivation has been continued for a considerable time, there is every mark of a much higher degree of inanition than when the disease has been removed by mercury without any sensible evacuation. There can remain no doubt, then, that the cure of lues venerea is by no means in proportion to the evacuation which it produces. This, however, should necessarily be the case, were the cure effected by evacuation.
Upon the whole, then, from what has been said of this theory of the action of mercury in the cure of the lues venerea, it appears, that the cure can by no means be referred to the evacuation. The different arguments adduced in favour of that theory, we have endeavoured to shew, either proceed on wrong principles, or, although admitted in their greatest latitude, can afford no ground for any conclusion to support it. Evacuation, from its nature, whether supposed to operate by diminishing the quantity of circulating fluids, or by any change it can induce in their quality, can scarce be conceived to be a cause adequate to the cure of lues venerea. Evacuation does not produce a cure of the venereal disease, when it takes place in an equal, or even in a much greater degree, from the employment of other medicines, than when the disease is effectually removed from the use of mercury. And, lastly, the venereal disease is never more effectually cured by mercury, than when it is evident, from every mark by which the degree of evacuation can be determined, that the evacuation arising from it is least considerable. It may, therefore, with confidence be asserted, that mercury does not cure lues venerea by evacuation.
CHAP. III.
Concerning the Opinion, that Mercury cures Lues Venerea, by acting as an Antidote to the Venereal Matter.