108 JOSEPH PRIESTLEY. [LEOT. 



membership upon him. Edinburgh had made him 

 an honorary doctor of laws at an early period of his 

 career ; but, I need hardly add, that a man of Priest- 

 ley's opinions received no recognition from the uni- 

 versities of his own country. 



That Priestley's contributions to the knowledge of 

 chemical fact were of the greatest importance, and 

 that they richly deserve all the praise that has been 

 awarded to them, is unquestionable ; but it must, at 

 the same time, be admitted that he had no compre- 

 hension of the deeper significance of his work ; and, 

 so far from contributing anything to the theory of the 

 facts which he discovered, or assisting in their rational 

 explanation, his influence to the end of his life was 

 warmly exerted in favour of error. From first to last, 

 he was a stiff adherent of the phlogiston doctrine 

 which was prevalent when his studies commenced; 

 and, by a curious irony of fate, the man who by the 

 discovery of what he called " dephlogisticated air" 

 furnished the essential datum for the true theory of 

 combustion, of respiration, and of the composition of 

 water, to the end of his days fought against the 

 inevitable corollaries from his own labours. His last 

 scientific work, published in 1800, bears the title, 

 "The Doctrine of Phlogiston established, and that 

 of the Composition of Water refuted." 



When Priestley commenced his studies, the current 

 belief was, that atmospheric air, freed from accidental 

 impurities, is a simple elementary substance, inde- 

 structible and unalterable, as water was supposed to 

 be. When a combustible burned, or when an animal 



