Michael Faraday 21 



to show that a current passing through a wire which is 

 made to move in the neighbourhood of another circuit 

 induces similarly a current in the latter; and finally he 

 extended these facts to the effects of moving magnets in place 

 of electric currents. Faraday thus not only prepared the way 

 for a consistent theory of electro-magnetic action, but proved 

 that it was possible to convert electric energy into mecha- 

 nical power, or, reciprocally, obtain electric energy by an 

 expenditure of mechanical work. In other words, the whole 

 of the present electric industry is based on his discoveries. 



As a second example of Faraday's experimental genius, 

 we may take his work on the chemical decomposition of a 

 liquid when an electric current is sent through it. Though 

 this process of electrolysis had been used with great success 

 by Sir Humphry Davy, its laws were not fully understood. 

 Faraday proved that the total quantity of the substance 

 decomposed depends only on the total quantity of electricity 

 which has passed, independently of whether it be a strong 

 current acting for a short time, or a weak current acting 

 for a correspondingly longer time. He also discovered a 

 most important relation between the amount decomposed 

 and the chemical constitution. In his own words : "If 

 we adopt the atomic theory and phraseology, then the 

 atoms of bodies which are equivalents to each other in 

 their ordinary chemical action, have equal quantities of 

 electricity naturally associated with them." How pregnant 

 these words are as forerunners of the most recent researches 

 in electricity will appear in due course. 



During a long life Faraday piled his discoveries one 

 upon another in almost continuous succession, yet they 

 are united by a common thread of thought applied both 

 consistently and persistently. New facts were brought 

 to light, not through an omnivorous desire to penetrate 

 into detached bits of unexplored regions, but by the wish 

 to find a common link binding together all the forces which 

 in each branch of Physics gravity, electricity, magnetism 

 and chemistry had been treated as peculiar to that branch. 

 His manner of looking at things was so different from that 

 of other scientific men of his time, and in some ways so 

 prophetic, that a few words must be said with regard to 



