232 EIGHTEENTH CENTURY. pt. hi. 



1742), a small apothecary at Kjoping, a little village in 

 Sweden. 



There is no doubt that Scheele deserves as much credit 

 for this discovery as if Priestley had never made it, for he had 

 not heard of his experiments, and he added many useful 

 facts which Priestley did not know. Still, as they both went 

 over much the same ground, we cannot aiford space here to 

 give Scheele's experiments. You must not, however, forget 

 his claim, for though the world often forgot him because he 

 remained a poor apothecary all his life, yet Scheele wms 

 really one of the first chemists of Europe. We owe to him 

 the discovery of chlorine ; and of manganese, barytes, fluor- 

 spar, and many other earths whose names I cannot expect 

 you to know. Indeed, his merit was so great that Bergmann, 

 his friend and patron, once said, * The greatest discovery he 

 ever made was when he discovered Scheele.' 



Joseph Priestley, the discoverer of oxygen, was born in 

 1733. The greater part of his life was spent in writing upon 

 religious subjects, and it was only in his leisure hours that 

 he studied chemistry. He tells us in his autobiography that 

 he first began to take an interest in such things in conse- 

 quence of visiting a brewery next door to his house and 

 watching the fixed air which rose from the beer-vats. His 

 first chemical experiment of any value was to force this * fixed 

 air ' into pure water, thus making an effervescing drink much 

 the same as the soda-water we drink now. He next tried 

 what effect growing plants have upon air, and by keeping a 

 pot of mint under a bell-jar in which the air had been spoilt 

 by burning or breathing, he proved that plants take up the 

 bad air and render the remainder fit again to support a 

 flame or life. He did not, however, yet know why this took 

 place. He also invented a number of troughs and other 



