334-

Materia Medica. — Hydrargyrum. part ii.

as there is every reason to suppose, these glands are endowedwith more irritability ' than the rest of the habit, it is easy toconceive that the same degree of stimulus, which is operatingon the whole system, will produce a greater effect on them ina direct ratio according to their greater susceptibility. Butalthough its general action is stimulant, yet the various prepar-ations of it produce different effects, operating sometimes as sti-mulants, sometimes as cathartics, or emmenagogues, and locallyas errhines : and hence the great variety of diseases in which ithas been found useful: as, febrile affections, spasms, cachetic dis-eases, glandular obstructions, cutaneous eruptions, and mem-braneous inflammation. (See Preparations and Compositions.)

But the most important effect of the preparations of mer-cury is their specific operation in syphilis. They were used,and their effects, when accumulated in the habit, were knownso early as the 13th century; and the writings of Theodorick 2contain cautions against catching cold during the course; butthe first notice of mercury as a remedy in lues venerea is con-tained in a tract by Jo. Almenar, a Spaniard, published in1516; who recommends it after the manner of the Arabians,but condemns pushing the remedy so as to promote salivation.Physicians, however, did not venture to give mercury inter-nally, till Paracelsus broke the fetters of ancient authority, andproved that it might be exhibited not only with safety, butwith advantage. Since his time, a period of nearly 300 years,experience has fully sanctioned its use; and, as Mr. Pearsonjustly observes, " not one medicine besides derived from theanimal, vegetable, or mineral kingdom, has maintained its cre-dit, with men actually employed in extensive practice during atenth part of that period':" yet, it is remarkable, that in thepresent day its utility in syphilis has been questioned. + Manyvarious theories of the operation of mercury have been ad-vanced ; the most satisfactory of which is that of Mr. Hunter,who supposed that the stimulant operation of the mercury in-duces and maintains an action which is incompatible with themorbid action produced by the venereal virus, until the poisonis either destroyed, or evacuated from the body by the excre-tories. But whatever may be the principles on which it ope-rates, its efficacy in this disease is certain, when it is judiciouslyand cautiously administered. The mode of giving it, and themorbid effects which it produces under certain circumstances,

i That the salivary glands and their excretories are very excitable, is evidentfrom the flow of the saliva being much increased by affections of the mind, as thethinking of any kind of food which is particularly grateful to the taste.

8 He was a friar, afterwards bishop of Cervia, and died between the years1270 and 80. See Freind's History of Physic, ii. 360.

3 Observations, &c. p. 97. 4 Medico-Chirurg. Trans, vol. ix,