From the supposition of a topical action in the manner here supposed, the fluid to be acted upon is, as it were, separate and distinct from the general mass. In this case, then, the objection, that the effects of the mercury will be taken off from the quantity of matter upon which it has to act, will not apply. At the same time there is here no necessity for having recourse to any hypothetical attraction between mercury and the venereal virus. It cannot, indeed, be alledged, that, in this case more than in the former, any obvious change occurs in the appearance of the venereal matter in consequence of the use of mercury. But the venereal matter, even in the most detached state in which it ever exists in the human body, is always blended with a certain proportion of pus and other humours. From this circumstance, we can never become acquainted with what is its real appearance. It cannot, therefore, be reasonably expected, that any changes which take place in it should become the object of observation. But observation sufficiently demonstrates a manifest difference in the effects produced by this virus, after the use of mercury, when compared with those which that virus before produced. That, therefore, in consequence of the employment of mercury, its nature is in reality changed, is but a reasonable conclusion. It was formerly adduced, as an argument in favour of another supposition, that the cure of _lues venerea_ produced by mercury was proportioned to the quantity of discharge which the mercury occasions. This assertion we have already attempted to show is by no means, in every case, true. It must, however, be allowed, that in some cases it does hold, and in those cases more especially where the discharge takes place from the system in general. To account for this on the theory here advanced, it is only necessary to consider in what manner such a discharge arises from the internal use of mercury. These evacuations are, without doubt, to be referred to the mercury reaching and acting upon the excretories by which they are made. The quantity of these discharges, then, will, in many cases, serve as a standard by which to determine the quantity of active mercury circulating in the system. But, in proportion to the quantity of mercury which circulates in the general mass of fluids, a greater or less quantity will come to be applied to every part in the body; and, among others, to those places in which the venereal matter exists. Upon the supposition, then, that mercury acts in the cure of _lues venerea_ as an antidote, it is easy to see how the cure should, in such cases, come to be proportioned to the quantity of the discharge.