It is, in general, imagined, that mercury may destroy the venereal virus in the mass of circulating fluids. The venereal virus is unquestionably taken into the human system by the absorbent vessels to which it is applied; and, before it can reach various parts of the body, in which it evidently manifests itself, it must enter the general mass of fluids. We cannot, then, consider it as a supposition totally absurd, that mercury, if it be capable of destroying the activity of the venereal matter, may produce that effect while the virus is present in the general mass of fluids. Many objections, however, may be urged against this supposition; and, if it be adopted, it must be allowed to be with difficulties. If mercury destroy the venereal virus, while it exists in the mass of circulating fluids, it must produce this effect, either by an alteration of the general mass; or by acting more particularly on the venereal matter itself. The whole mass of circulating fluids, taken collectively, is a very considerable quantity of matter. The action, therefore, of a small proportion of mercury, as producing any change upon it, cannot be very great. It is not easy to conceive, then, how a destruction of the venereal virus should arise from any alteration which the mercury is capable of producing on the general mass. The difficulty occurring to the first supposition here made, would naturally lead us to consider the second. But that the action of mercury, while it exists in the mass of circulating fluids, should be exerted on the venereal virus alone, is a supposition equally unsatisfactory as the former. Before this can be imagined to be the case, it is necessary to suppose, that there exists, between mercury and the venereal virus, some particular attraction. Such an attraction, however, is a thing as yet by no ways proved to exist; nor indeed does there seem to be any shadow of reason to suppose that it does exist. Although, then, it cannot be denied, that mercury and the venereal virus may exist in the mass of circulating fluids at the same time; yet, from what has been said, the supposition, that the activity of the virus is then destroyed, will appear to be attended with many difficulties. It cannot, it is true, be alledged, that, from any thing which has been urged, this supposition is refuted. That it may perhaps, in some degree, act in this way, is by no means impossible. But it is to be remembered that this is a hypothesis supported by no proof; and the more imaginary any opinion is, the less easily can it be overturned. The present opinion, then, may be set aside, for reasons, which, in other respects, would be insufficient for its being rejected; and this the more readily, if another and more probable hypothesis can be advanced which is not liable to the same objections.