LECTURE I. HISTORY OF CHEMISTRY. 7 



observed this in the cases of tin and of lead ; and the chemical 

 literature up to Stahl's time furnishes several statements of the 

 same kind. Highly interesting, for example, are the observa- 

 tions of Jean Rey, of Mayow and of Hooke, as well as the 

 conclusions which they drew from them. I shall enter into 

 these in the next lecture. 



Can we avoid being astonished when we read that Becher 

 and Stahl knew of these experiments and still defended their 

 views ; that they regarded the increase of weight merely as an 

 incidental, unimportant phenomenon ; and that either the 

 authority of the ancients, or the phenomenon of combustion 

 itself, which with them was so intimately associated with the 

 idea of destruction, was a sufficient ground for neglecting facts 

 which must otherwise have overthrown their edifice? It is 

 more particularly noteworthy, however, that Boyle one of the 

 most considerable thinkers of the seventeenth century, a pre- 

 decessor of Stahl, calling himself a follower of the Baconian 

 school ; who was aware, from his own experiments, of the in- 

 crease of weight on combustion ; who knew that the air was 

 necessary for this, and who had made the observation that 

 during combustion a part of the air is absorbed could not 

 make up his mind whether sulphuric acid was a constituent of 

 sulphur, or on the other hand whether sulphur was contained 

 in sulphuric acid. 5 



Amongst the successors of Stahl we find, it is true, some 

 who direct their attention more fully to this increase of weight. 

 Lemery, for example, towards the end of the seventeenth cen- 

 tury, states his views about it at length. 6 At the same time 

 his belief in the existence of phlogiston remains unshaken, 

 although combustion now becomes a sort of double phe- 

 nomenon. It remains a decomposition ; that is, the burning 

 substance separates from its phlogiston, but simultaneously it 

 unites with a ponderable fire material. Lemery obtained his 

 ponderable fire material from the same source as that from 

 which Becher had taken his terra pinguis and Stahl his 



5 Kopp, Geschichte, I, 166, 6 Ibid. 3, 123. 



