394 NINETEENTH CENTURY. PT. HI, 



silver-like globules, some of which burst into flame, while 

 others remained covered by a sort of white film. 



* Davy's delight,' writes his brother, * when he saw the 

 minute shining globules like mercury burst through the crust 

 of potash and take fire as they reached the air, was so great 

 that he could not contain his joy he actually bounded 

 about the room in ecstatic delight.' It must indeed have 

 been a beautiful sight in itself; but probably Davy's excite- 

 ment arose chiefly from the new truth he saw in it. He had 

 proved that potash was not a simple substance, but contained 

 something which had never before been discovered. 



At first he had great difficulty in collecting the globules, 

 for they not only burst into flame when they met the air, 

 but even in water they took fire, joining themselves to the 

 oxygen and setting the hydrogen free. At last, however, he 

 succeeded in collecting them in rock oil, or naphtha, which 

 contains no oxygen. He was then able to examine them, 

 and he found they were composed of a metal hitherto quite 

 unknown, to which he gave the name of potassitim. A few 

 days later he procured the metal sodium out of common 

 soda by the same process. 



This method of decomposing substances is called electro- 

 lysis, which means ' setting free by electricity.' Davy made 

 use of it to decompose many earths, such as lime, magnesia, 

 etc., and the great Swedish chemist, Berzelius (born 1778 

 died 1848), discovered several new chemical substances by 

 means of it. 



Faraday's Experiments 6n the Connection between 

 Electricity and Chemical Affinity* The power of de- 

 composing substances was the practical benefit obtained 

 by the discovery; but it had another great interest for 

 chemists, because it proved that electricity can overcome 

 that power called 'chemical affinity,' which holds two 01 



