i8 2 SCIENCE AND THE HUMAN MIND 



electromotive force. The chemical decompositions 

 produced by these currents were the first of their pro- 

 perties to be investigated, and led to the industry 

 of electro-plating, while, more recently, they have 

 been used extensively in many processes of chemical 

 manufacture and in metallurgical operations. 



In theoretical science, one of the earliest and most 

 striking of the results of the use of the voltaic cell 

 was the separation in 1807 of the alkali metals potas- 

 sium and sodium from their oxides in the researches 

 of Sir Humphry Davy (1778-1829). Davy, a native 

 of Penzance, was the first Professor of Chemistry at 

 the newly founded Royal Institution. It is a sign of 

 the growing general interest in science that an institu- 

 tion for diffusing scientific knowledge should have 

 come into existence, and that Davy's lectures should 

 have attracted a large audience composed both of 

 " men of science and numbers of people of rank and 

 fashion." Davy's attractive personality had much 

 to do with this success, while his imaginative and 

 poetic nature was an essential part of his power as a 

 framer of scientific hypotheses fit to be tested by 

 experiment. 



Electrically, Davy's work marks an important step. 

 The use of electrical forces to separate chemical com- 

 pounds into simpler constituent parts indicates a 

 connection between electrical and chemical phenomena 

 which is of fundamental importance in the theory 

 of both subjects. Davy's work was taken up again 

 and carried further by his pupil and successor, Michael 

 Faraday (1791-1867), whose instinctive genius we shall 

 meet again in future pages. Faraday showed that 

 the amount of chemical action was strictly proportional 



