16 JOSEPH PRIESTLEY i 



tubs, he discovered more new gases than all his 

 predecessors put together had done. He laid the 

 foundations of gas analysis ; he discovered the 

 complementary actions of animal and vegetable 

 life upon the constituents of the atmosphere ; and, 

 finally, he crowned his work, this day one hundred 

 years ago, by the discovery of that " pure dephlo- 

 gisticated air " to which the French chemists 

 subsequently gave the name of oxygen. Its 

 importance, as the constituent of the atmosphere 

 which disappears in the processes of respiration and 

 combustion, and is restored by green plants growing 

 in sunshine, was proved somewhat later. For 

 these brilliant discoveries, the Royal Society elected 

 Priestley a fellow and gave him their medal, while 

 the Academies of Paris and St. Petersburg con- 

 ferred their 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 Priestley's opinions received no 

 recognition from the universities 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 comprehension of the deeper significance of his 

 work ; and, so far from contributing anything to 

 the theory of the facts which he discovered, or 



