[12] Ib. iii. 472.
[13] Ib. iii. 482.
[14] Ib. iii. 475.
[15] Vol. v. 315.
I have already, in the History of Chemistry[16], stated, that the doctrine of the opposition of acid and alkali, the great step which theoretical chemistry owes to Sylvius, was first brought into view as a physiological [178] tenet, although we had then to trace its consequences in another science. The explanation of all the functions of the animal system, both healthy and morbid, by means of this and other chemical doctrines, and the prescription of methods of cure founded upon such explanations, form the scheme of the iatrochemical school; a school which almost engrossed the favour of European physicians during the greater part of the seventeenth century.
[16] Hist. Ind. Sc. b. xiii. c. 2.
Sylvius taught medicine at Leyden, from the year 1658, with so much success, that Boerhaave alone surpassed him[17]. His notions, although he piqued himself on their originality, were manifestly suggested in no small degree (as all such supposed novelties are) by the speculations of his predecessors, and the spirit of the times. Like Helmont[18], he considers digestion as consisting in a fermentation; but he states it more definitely as the effervescence of an acid, supplied by the saliva and the pancreatic juice, with the alkali of the gall. By various other hypothetical processes, all of a chemical nature, the blood becomes a collection of various juices, which are the subjects of the speculations of the iatrochemists, to the entire neglect of the solid parts of the body. Diseases were accounted for by a supposed prevalence of one or the other of the acrid principles, the acid or the alkaline: and Sylvius[19] was bold enough to found upon these hypotheses practical methods of cure, which were in the highest degree mischievous.
[17] Spr. iv. 336.
[18] Ib. 338.
[19] Ib. iv. 345.