vi] Sylvius and his Pupils. 167 



duct, than to a fluid which seemed simply to ooze from a 

 membranous surface ; and these were led to regard the change 

 in the stomach as brought about not by the independent action 

 of a ferment belonging, as van Helmont had thought, to the 

 stomach itself, but by such a ferment with the help of the 

 swallowed saliva, or even by the saliva itself. 



After the works which I have just mentioned we have to 

 wait a long time, for many years, for in fact the greater part 

 of a century, before we come upon another solid addition to our 

 knowledge of the subject. 



It is true that during the remainder of the seventeenth 

 century new truths about chemistry, new views about chemical 

 action were being continually gathered in. It is true that 

 at the close of the seventeenth and the beginning of the 

 eighteenth century there flourished two men who achieved 

 great eminence as chemists and who were assiduous in applying 

 their chemical knowledge to physiology; but so far at least 

 as digestion is concerned their influence was that rather of 

 expositors than of discoverers. One of these was George Ernest 

 Stahl, who was born at Anspach in 1660 at the time when Sylvius 

 was in his fullest vigour. After studying and graduating at Jena, 

 he became Court physician at Weimar, and in 1694 Professor of 

 Medicine at Halle; but in 1716 being made physician to the 

 King of Prussia, he moved to Berlin, where he died in 1734. He 

 was an accomplished chemist, and his name must always be 

 borne in mind in dealing with the history of science, if for 

 nothing else for the reason that he was the author of the 

 famous theory of phlogiston, which ruled with a rod of iron, as 

 it were, the thoughts of natural philosophers for a hundred 

 years. 



His general views he seems to have learnt, in the first 

 instance, from Wedel, his teacher at Jena, who was an ardent 

 spiritualist and who wrote a tract on the archseus; but in 

 chemistry he sat at the feet of Johann Joachim Beccher, of whose 

 Physica Subterranea, a treatise on chemistry, he published an 

 edition in 1703. Beccher developed at some length his views 

 on the essential principle of fire, but does not seem to have 



