It is alledged, that mercury cures _lues venerea_ by the evacuation it occasions; because the good effects derived from its employment are observed to be more in proportion to the stimulant power of the preparation which is used, than to the quantity of mercury taken. The data, however, here assumed by no means lead to the conclusion deduced from thence. The most stimulant preparations of mercury, by their action on the _primæ viæ_, are in general immediately expelled from the system. When this happens, they have no influence in the cure of venereal complaints. When they are not thus expelled, their nature is such that they most readily enter the system. Their superior action, then, may be accounted for without supposing that it depends on their producing the most considerable evacuation. From the facts as here stated, it indeed follows, that the good effects obtained from mercury are greatest in those cases in which the mercury enters the system in most considerable quantity. The evacuation, it is true, is then likewise greatest. But this will unquestionably follow as the necessary consequence of the presence of active mercury in the system, and can by no means be concluded to be the cause of the cure. The evacuation which occurs in this case, then, as was observed in the objections adduced against the last argument, can be considered only as an index of the quantity of active mercury which is present in the system. The superior activity, therefore, which some stimulant preparations possess, when compared with those of a milder nature, is by no means a proof of the supposition that mercury cures _lues venerea_ by means of the evacuation which it produces; and this argument, as well as the former, may be set aside. The third argument mentioned in favour of this theory, and the last which we proposed to consider, is, that the same good effects, in the cure of _lues venerea_, may be obtained from the employment of other evacuants, as from that of mercury; and particularly, that the venereal disease is cured in a similar manner by the use of guaiac. This argument, if well founded, would indeed be a conclusive proof of the theory, in support of which it is here adduced. Evacuation may be occasioned by a great variety of other means besides mercury. The influence of any discharge, as tending to cure _lues venerea_, will fall more particularly to be considered in stating the objections against this theory. A full answer, then, to the first part of this argument, would at present be superfluous: But it may be observed, that it is by no means a common practice to attempt the cure of _lues venerea_ by the safest and most effectual evacuants now in use; and that, when evacuants are employed for the cure of other diseases, while a venereal infection at the same time exists in the system, it is never found to yield to them. This first part of the argument, then, may be shortly answered, by denying it to be true.