Part 3

By very intense cold, artificially excited, mercury may be brought to a solid form; but, in the greatest natural cold hitherto known, it remains always in a fluid state. By heat it is rendered very volatile, exhaling totally in fumes; these fumes, upon being exposed to cold, condense again into running mercury.

Mercury, like most other metallic substances, is found in the earth, either in a pure state, or in that of an ore. The first has been called virgin-mercury, and is in general found by the miners in drops or small grains; sometimes indeed it is observed in larger quantities, and forms the appearance of small streams. In the state of ore, it is most frequently combined either with sulphur, or with earthy matters; from which it is readily extracted by distillation. It is found in both these states in different places of Europe, particularly in Spain and in Hungary; but Britain is principally supplied with it from the East-Indies.

Mercury was not unknown to the antients. In the early ages of medicine, indeed, it seems to have been esteemed a virulent poison; but it has now, for some centuries past, been much, and successfully, employed for the purposes of medicine, as well as of other arts.

The Arabians were the first who employed it in the cure of diseases; but they seem to have used it externally only, and applied it for discussing tumors, cleansing ulcers, and curing cutaneous eruptions. Soon after the introduction of the venereal disease into Europe, mercury was found to be the most expeditious and most effectual, if not the only certain, remedy. The advantages which are to be derived from its employment in this disease, both when applied externally, and taken internally, have now been confirmed for a length of time too considerable for allowing the least foundation either to doubt its efficacy, when properly used, or to dread its deleterious effects, when judiciously managed.

The effects of mercury on the human system in a sound state are very various. When mercury, in its crude state, is introduced by the mouth into the alimentary canal, it passes off by stool, without producing any effect. It has indeed been alledged, that in this state, in some morbid affections, it may be useful in removing obstructions by its weight. But it is to be remembered, that, in a great part of its passage through the intestines, it rises in opposition to gravity, and that it is very apt to divide in such a manner as to make its way through very small openings. This effect, then, is perhaps in general, if not always, to be disregarded.

When mercury is prepared in such a manner as to be readily soluble in the fluids of the human body, the effects it produces are much diversified. Its action is often immediately exerted upon the stomach; in which case vomiting is produced. This effect is observed from the use of many mercurial preparations. The brown and green precipitates and calcined mercury act as rough and strong emetics; but the preparation principally used, where it is intended to act as an emetic, is the yellow precipitate, or Turpeth mineral.

Many of those mercurials, which have not such an influence upon the stomach as to produce vomiting, upon entering the intestinal tube, act as purgatives. This effect of mercurials is, among other preparations, particularly remarkable on the use of the Coralline mercury, Prince’s powder, or calomel.

Mercurials, which fail in producing either purgative or emetic effects, frequently act as diaphoretics. Diaphoresis, or even a profuse sweat, is often the consequence of many of the mercurials already mentioned. But when this effect is wanted, by means of mercurials, it is most commonly obtained by the use of a solution of corrosive sublimate.

Mercury entering the circulating system exerts particular effects on different excretories; but in a more especial manner on those of the saliva. Salivation is an effect which may be obtained from the proper administration of almost every mercurial preparation; but for this purpose either the mercurial pills, or friction with mercurial ointment, are most frequently employed.

Mercury may enter the system, exist in considerable quantity there, and be carried off by the different excretories, without producing any remarkable evacuation, or other apparent change, on the sound state of the body. That it is actually present in the system in such cases, is demonstrated by a general tendency to an increase in all the secretions. Mercury in this way, although it produces no visible effect on a healthy person, often procures the removal of a diseased state. Its action, therefore, in such circumstances, is termed alterative; an effect which may be obtained from most of the mild mercurials, especially when used in small doses.

From these various modes of operating, it may readily be concluded, that mercury must be a powerful remedy in the cure of many diseases. The undoubted effects which it produces on the human system, when labouring under the venereal distemper, it would be both difficult and unnecessary fully to enumerate. It heals ulcers, removes swellings, alleviates pains, and cures eruptions. In short, the almost infinite variety of symptoms under which this disease makes its appearance may, by a proper application of mercury, be effectually eradicated from the constitution.

From these effects, it is not surprising, that, in this distemper, mercury is the almost universal remedy. But, while it cannot be denied that peculiar advantages may be reaped from the employment of mercury in the venereal disease, it must at the same time be acknowledged, that, from the injudicious use of this medicine, very great evils have been produced. Whatever, therefore, relates to its proper administration, must be esteemed of importance. But to determine this, it is in the first place requisite to ascertain the principles upon which it operates. In treating of the present subject, then, an examination of the most probable opinions, with regard to the mode of its operation in the venereal disease, first claim our attention.

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CHAP. II.

Concerning the Opinion, that Mercury cures the Lues Venerea by the evacuation it produces.

THERE are few medicines with regard to the operation of which all practitioners are agreed. It is, however, by no means incumbent on him who means to establish the truth of any one opinion to overturn every hypothesis advanced on the same subject. But, as the arguments urged in favour of any hypothesis will have much less weight when another is previously believed to be true, and as the regulation of practice is, in every case, to a certain extent, founded upon theory, no inconsiderable advantage may be derived from overturning an ill-founded opinion, especially when it is generally received. The theory of the action of mercury, as well as of other substances, has afforded room for a diversity of opinions. For the reasons mentioned above, then, although it is by no means intended, that every opinion, with regard to the operation of that medicine, should here be considered; yet, as it is a very prevailing opinion, that the good effects obtained from mercury in the cure of lues venerea, depend upon its action as an evacuant; and, as a variety of seemingly strong arguments have been adduced in favour of that hypothesis, it will be necessary to examine how far they are sufficient to establish its truth.

In favour of the opinion, that mercury cures lues venerea by acting as an evacuant, the following arguments have been employed. It is alledged, that the good effects obtained from mercury in the cure of this disease, are in proportion to the evacuation which it produces; that the cure produced by mercury depends more upon the stimulant power of the preparation which is employed, than upon the quantity taken; and that the same good effects are obtained from other evacuants as from mercury; particularly, that the venereal disease is cured in a similar manner from the employment of guaiac. The arguments here enumerated, if not the only ones upon which this opinion is founded, are at least those which are principally employed. To examine, then, how far these are well founded, will be sufficient.

The first argument here adduced is, that the good effects of mercury are proportioned to the evacuation which it produces. This assertion, if allowed to be true, might, at first sight, appear to be a very strong argument in favour of the theory here adopted. But it is strong in appearance only; for, although it should be admitted, it in fact proves nothing.

But, even previous to this, it might be made a question, how far what is here assumed as a fact is well founded? And if it should appear, that mercury does not cure lues venerea in proportion to the evacuation which it produces, a strong argument might from thence be brought against this theory. But what may be said on this question will, with greater propriety, occur when the objections to the theory come to be adduced, than in attempting to refute and invalidate the arguments brought in its favour. At present, it will be sufficient to show, that, even allowing it to be true, it is no argument in favour of the supposition.

If it be true, that mercury cures lues venerea in proportion to the evacuation it produces, it may indeed, with some degree of probability, be concluded, that the evacuation and cure are not unconnected. And, if the evacuation is not the cause of the cure, it might at least from thence be inferred, that both of them depend upon the same cause; but it no more, unquestionably, follows from thence, that the evacuation is the cause of the cure, than that the cure produces the evacuation.

The degree of evacuation which, in any case, arises from the employment of mercury, will, it is natural to imagine, be proportioned to the quantity of active mercury which is introduced into the system. But, in whatever way mercury acts in the cure of the venereal disease, it may then be supposed to act most powerfully when it is present in the system in most considerable quantity. In this point of view, then, the evacuation which arises from the use of mercury is to be considered merely as an index of the quantity of the medicine which is introduced into the system in an active state; and the cure may be proportioned to the evacuation, only as pointing out the degree in which the mercury exists in the habit. Even supposing, then, that the foundation upon which this argument is built were not to be called in question, yet, taken in its greatest latitude, it is still at best but doubtful; and from it no conclusion can be drawn in favour of the theory which it is brought to support.

The second argument mentioned in proof of the supposition that mercury acts, in the cure of lues venerea, as an evacuant, was, that the cure produced by mercury depends more upon the stimulant power of the preparation employed, than upon the quantity of mercury which is used.

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.

But it was likewise alledged, that mercury, used at different times, although given in equal quantities and in the same form, produces very different effects. Crude mercury, as has already been observed, although swallowed in considerable quantities, rarely produces any other effect on the body, than what arises from the passage through the alimentary canal. This, however, although generally, is not universally the case. On some occasions, when taken in this way, it operates with as great activity as when used in any other form; and, from many well attested instances, it appears, that, by being swallowed even in a crude state, a high salivation has been excited. In this we have an instance in which a remarkable difference of effect arises from the employment of the same preparation at different times. This difference cannot arise from the quantity of mercury employed; for while, in some cases, no operation of the nature here mentioned takes place from the use of a large quantity, in others, it will be excited where an inconsiderable quantity only has been taken. The difference of effects here observed, then, must be ascribed to some other cause; and it is most reasonable to refer it to particular accidents in the constitution at the time the medicine is used. In these cases, where no operation takes place from its use, it may be concluded, that the whole quantity of mercury swallowed has passed through the alimentary canal in the same state in which it was taken in. When, on the other hand, an operation upon the salivary glands, or any other excretory remote from the alimentary canal, is observed from the use of crude mercury, it may be concluded, that part of the mercury, from some peculiarity in the habit at the time, such, for example, as the presence of superabundant acid in the stomach, has been brought into such a state as to be capable of entering the circulating system. From these instances, then, it evidently appears, that the facility with which mercury enters the system, admits of very great variety. And from this a strong objection may be adduced against the argument here brought to support the hypothesis that mercury cures lues venerea by its evacuant power.

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.