446

ELEMENTS OF MATERIA MEDICA.

and alkalies do on each other; while Girtanner ( Alhandl. u. d. Verier.Krankh.) supposed that the efficacy of mercurials depended on theoxygen they contain. To both hypotheses the same objection applies:if they were true, the larger the quantity of mercury used, the moreeffectually would the venereal disease be cured. Now this is not foundto be the case. Dr. Cullen {Treat, of the Mat. Med. ii. 446) endea-voured to account for the action of mercury on the salivary glands, inpreference to other organs, by assuming that it has a particular disposi-tion to unite with ammoniacal salts, with which it passes off by thevarious excretions; and as the saliva was supposed to contain more ofthese salts than other secretions, he thus accounted for the larger quantityof mercury which passed off by these glands, and which being in this wayapplied to the excretories, occasioned salivation. But the whole hypo-thesis falls to the ground, when it is known that mercury has no “ par-ticular disposition” to unite with the ammoniacal salts ; and that, evenif it had, other secretions are as abundantly supplied with these salts asthe saliva. Dr. John Murray substituted another hypothesis, but equallyobjectionable:—mercury, says he, cannot pass off’ by the urine, becauseof the phosphoric acid contained in this fluid, and which would form,with the mercury, an insoluble compound. It must, therefore, be thrownout of the system by other secretions, particularly by the saliva, whichfacilitates this transmission by the • affinity which the muriatic acid, thesoda, and the ammonia of the secretion, have for the oxide of mercury,and by which a compound soluble in water is formed. The answer tothis hypothesis is, that mercury is thrown out of the system by the urine,and probably in larger quantity than by the saliva; secondly, the salivaalso contains plmsphatic salts, according to Tiedemann and Ginelin,

(c.) Dynamical hypotheses. —Some writers have principally directedtheir attention to the quality of the effects induced by mercury, and havetermed this mineral stimulant, sedative, both stimulant and sedative, tonicor alterative. Those who assume mercury to be a stimulant or excitant arenot agreed as to whether particular parts or the whole system are stimu-lated, and, if particular parts, what these are. Thus Hecker fixes on thelymphatic system, Schone on the arterial capillary system, Reil on thenerves (Richter, op. cit. v. 306). The simple answer to all of them is, thatother stimulants are not capable of producing the same effects on theconstitution as mercury; nay, are frequently hurtful in the very casesin which this metal is beneficial.

On the other hand, Conradi, Bertele, and Horn (quoted by Richter,op. cit. v. 307), considered it to be a weakening agent, or sedative.Hence those who adopt this hypothesis must assume that the diseases inwhich mercury is beneficial are of aphlogi . uc or hypersthenic character;and that syphilis, therefore, is of this kind, — an explanation not atall satisfactory, nor consistent with facts. Of late years, the sedativeoperation of some of the mercurial preparations (calomel and mercurialointment) has been assumed (particularly by our countrymen practisingin the East), from the circumstance that these agents allay vomiting anddiarrhoea in yellow fever, cholera, and other dangerous diseases. Buteven admitting that mercurials do produce these effects, this is hardly asufficient ground for denominating them sedatives.

Some think that mercurials, in small or moderate doses, are stimulants,but in excessive doses, sedatives; and that this sedative operation is