STEPHEN HALES 117 



[Hist. Bot., Eng. Tr., p. 477). Another great man 

 influenced Hales, namely Robert Boyle, who was 

 born 1627 and died 1691. John Mayow again, 

 that briUiant son of Oxford, whose premature 

 death at 39 in 1679 was so heavy a blow to science, 

 belongs to the same school as Hales — the school 

 which was within an ace of founding a rational 

 chemistry, but which was separated from the more 

 obvious founders of that science by the phlogiston- 

 theory of Becchers and Stahl. I do not find any 

 evidence that Hales was influenced by the phlogistic 

 writers, and this is comprehensible enough, if, as 

 I think, he belongs to the school of Mayow and 

 Boyle. 



The later discoverers in chemistry are of the 

 following dates. Black 1728 — 1799, Cavendish 

 1 73 1 — 1 810, Priestley 1733 — 1804, Scheele 1742 — 

 1786, Lavoisier 1743, guillotined 1794. These 

 were all born about the time of Hales' zenith, nor 

 did he live^ to see the great results they accom- 

 plished. But it should not be forgotten that Hales' 

 chemical work made more easy the triumphant 

 road they trod. 



I have spoken of Hales in relation to chemists 

 and physicists because, though essentially a physi- j 

 ologist, he seems to me to have been a chemist anoj 

 physicist who turned his knowledge to the study 

 of life, rather than a physiologist who had some 

 chemical knowledge. 



Whewell points out in hislHistory of the Inductive 



^ Black's discovery of CO?, however, was published in 1754, 

 seven years before Hales died, but Priestley's, Cavendish's and 

 Lavoisier's work on O and H was later. 



