A HISTORY OF SCIENCE 



substance in its place, and how the original metal 

 could be restored by the addition of wheat to the cal- 

 cined product. To the alchemist this was " mortifica- 

 tion" and "revivification" of the metal. For, as 

 pointed out by Paracelsus, "anything that could be 

 killed by man could also be revivified by him, although 

 this was not possible to the things killed by God." 

 The burning of such substances as wood, wax, oil, etc., 

 was also looked upon as the same "killing" process, 

 and the fact that the alchemist was unable to re- 

 vivify them was regarded as simply the lack of skill 

 on his part, and in no wise affecting the theory 

 itself. 



But the iconoclastic spirit, 'if not the acceptance of 

 all the teachings, of the great Paracelsus had been grad- 

 ually taking root among the better class of alchemists, 

 and about the middle of the seventeenth century Rob- 

 ert Boyle (1626-1691) called attention to the possibility 

 of making a wrong deduction from the phenomenon of 

 the calcination of the metals, because of a very im- 

 portant factor, the action of the air, which was gen- 

 erally overlooked. And he urged his colleagues of 

 the laboratories to give greater heed to certain other 

 phenomena that might pass unnoticed in the ordi- 

 nary calcinating process. In his work, The Sceptical 

 Chemist, he showed the reasons for doubting the 

 threefold constitution of matter; and in his General 

 History of the Air advanced some novel and carefully 

 studied theories as to the composition of the atmos- 

 phere. This was an important step, and although 

 Boyle is not directly responsible for the phlogiston 

 theory, it is probable that his experiments on the 



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