This argument may be answered in the same manner with the preceeding. It is indeed true, that different preparations of mercury, when used in equal quantities, have by no means equal influence in the cure of _lues venerea_. There is seldom an opportunity of observing what would be the effects of the most stimulant preparations, as, in the venereal disease, they are by no means in common use; and as, from their action on the alimentary canal, they exert very violent effects, without entering the circulating system. They, in general, operate very roughly, both as emetics and purgatives; but it is not clear that, in the venereal disease, any benefit has been obtained from their effects in either of these ways. It can therefore by no means be allowed, that the foundation of this argument, in its full extent, is strictly true. It cannot indeed be denied, that some preparations of mercury, which possess a considerable stimulant power, have a greater influence in the cure of _lues venerea_, than several others which are less stimulant. So far, then, the foundation upon which this argument is built, must be allowed to be just, and its weight, as tending to establish this theory, requires a refutation. But, even admitting it to be just, without any reserve, still, no more than from the former, can any conclusion be drawn from this in favour of the theory which it is meant to support. It has already been observed, that, in whatever way mercury operates in the cure of _lues venerea_, its good effects may always be supposed to be proportioned to the quantity of the medicine which enters the system in such a state as to become active there. But the quantity of active mercury entering the system can in no case be judged of from the quantity of the preparation which is employed. One preparation of mercury much more readily admits of a mixture with the animal fluids than another; in consequence of this, it will find a more ready entrance into the system. And further, this variety in the facility of access into the system, not only holds in different preparations, but even in the same preparation at different times. In proof of the first of these propositions, we have a convincing example in the difference which is observable between the effects arising from the use of crude mercury, and of this metallic substance, when no other means are used to render it active than simple trituration. It is well known, that even a very inconsiderable quantity, taken in this last way, will soon shew its effects at the most remote excretories of the body; in the other, although swallowed to the quantity of many pounds, it is a very rare occurrence that any effects can be observed from which it can be concluded, that it has, in any degree, entered the mass of circulating fluids.