From these circumstances it is easy to see, that, upon the theory formerly adopted, the introduction of mercury into the system is, in many cases, not only proper, but even necessary. But, at the same time, the advantages which, from that theory, we are led to expect from the immediate application of mercury to parts affected by the venereal virus are not less true. As the first method of using mercury was by external application, for an action on the parts affected; so external application was likewise the first means employed for introducing it into the system. For that purpose, all the various modes of applying mercury, which have already been mentioned, have, at different times, been used. Applications of mercury to the surface of the body by unction, plaster, fumigation, and lotion, have each, at different times, and by different practitioners, been recommended as the safest and most effectual method of introducing it into the system. But, after longer and more accurate observation than could at first be obtained, the application of mercury in the form of unction is the only method of introducing it into the system, by external application, which is now in practice. Whatever may be the means used for introducing mercury into the system, it is certain, that, if it do enter it in an active state, it will cure the disease. Its introduction by unction is still by no means an uncommon practice. By several modern practitioners, this method of introducing it into the system is still recommended, as preferable to every other. When properly viewed, however, it must be allowed, that if it be attended with advantages on the one hand, it is by no means free from inconvenience on the other, and in certain circumstances only is a preferable practice. In the mercurial ointment, the preparation which is here used, the mercury, as was formerly observed, is rendered active from division by triture. The mercurials prepared in this manner are in general the mildest in which mercury is in an active state. It may be laid down as an undoubted fact, without pretending in this place to assign any cause for it, that the milder mercurial preparations have a greater tendency to operate by salivation than the more acrid. But there is perhaps no method of exhibiting mercury in which it more certainly operates by salivation, than when it is applied externally in the way of unction. After what has been said by the greatest authorities in medicine against salivation, it would be unnecessary to add any thing here. It may be sufficient to observe, that it has been pronounced to be a practice not only attended with very great inconvenience, and no inconsiderable danger, but even unnecessary. The tendency, therefore, which this mode of introducing mercury into the system has of exciting salivation, may be considered as no small objection to its being put in practice.