ELECTRICITY AND MAGNETISM 



brass wires connected with the poles of a voltaic pile, 

 composed of alternate silver and zinc plates, so that 

 the current coming frpm the pile was discharged 

 through a small quantity of " New River water." " A 

 fine stream of minute bubbles immediately began 

 to flow from the point of the lower wire in the tube 

 which communicated with the silver," wrote Nichol- 

 son, " and the opposite point of the upper wire became 

 tarnished, first deep orange and then black. ..." The 

 product of gas during two hours and a half was two- 

 thirtieths of a cubic inch. "It was then mixed with 

 an equal quantity of common air," continues Nichol- 

 son, "and exploded by the application of a lighted 

 waxen thread." 



This demonstration was the beginning of the very 

 important science of electro-chemistry. 



The importance of this discovery was at once recog- 

 nized by Sir Humphry Davy, who began experiment- 

 ing immediately in this new field. He constructed a 

 series of batteries in various combinations, with which 

 he attacked the "fixed alkalies," the composition of 

 which was then unknown. Very shortly he was able 

 to decompose potash into bright metallic globules, re- 

 sembling quicksilver. This new substance he named 

 " potassium." Then in rapid succession the elementary 

 substances sodium, calcium, strontium, and magnesi- 

 um were isolated. 



It was soon discovered, also, that the new electricity, 

 like the old, possessed heating power under certain 

 conditions, even to the fusing of pieces of wire. This 

 observation was probably first made by Frommsdorff, 

 but it was elaborated by Davy, who constructed a, 



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