410 WELLS'3 NATURAL PHILOSOPHY. 



with the battery tho current passes, renders the platinum red-hot, and eXs 



plodea the the powder.* 



„ , The (greatest artificial heat man has yet succeeded in pro- 



IIow may the , . , , , , , „ "^ , , . , -^ 



greatest artifi- ducmg lias been through the agency oi the gaivamc battery. 



cial heat be ^jj ^)^q metals, including platinum, which can not be fused 

 produced? ' ° ^ ' 



by any furnace heat, are readily melted. Gold bums with a 



blueish light, silver with a bright green flame, and the combustion of the 



other metals is always accompanied with brilliant results. All the earthy 



minerals may be liquefied by being placed between the poles of a sufficiently 



large battery. Sapphire, quartz, slate, and lime, are readily melted ; and 



the diamond itself fuses, boils, and becomes converted into coal. 



How are the ^^^' The luminous eflects of the galvanic 

 focts'^^of the hattery are no less remarkable than its heating 

 fe^^^manifest- sfFects. A vcrj Small voltaic arrangement is 

 "^^ sufficient to produce a spark of light every 



time the circuit is closed or opened. If the two ends of 

 wires proceeding from the opposite poles of a battery are 

 brought nearly together, a bright spark will pass from one 

 to the other, and this takes place even under water, or in 

 a vacuum. 



How may the Tlic most splcudid artificial light known ia 

 raificiari'i^ht produced by fixing pieces of pointed charcoal 

 be produced? ^q ^^q wircs counectcd with opposite poles of a 

 powerful galvanic battery, and bringing them within a short 

 distance of each other. The space between the points is 

 occupied by an arch of flame that nearly equals in dazzling 

 brightness the rays of the sun. 



This light, which is termed the electric light, differs from 



electric li"iit ^11 other forms of artificial light, inasmuch as it is independent 



differ from nil of ordinary combustion. The charcoal points appear to suffer 



lights? no cliange, and the light is equally strong and brilliant in a 



vacuum, and in such gases as do not contain oxygen, whera 



• In the course of the construction of a railway recently in England, it bocame neces- 

 cary to detach a large mass of rock from a cliff on the sea-cuast in order to avoid the ex- 

 pense of a long tunnel. To have done this by the direct application of human labor and 

 the ordinary operations of blasting, would have been attended with an immense expendi- 

 ture of time and money. It was accordingly resolved to blow it up with gunpowder, 

 ignited by the galvanic battery. Nine tons of powder were accordingly deposited in cham- 

 bers at from 50 to 70 feet from tho face of the cliflT, and fired by a conducting wire connected 

 ■with a powerful battery, placed at 1,000 feet from the mine. The explosion detached 

 600,000 tons' weight of chalk from the cliff. It was proved that this might h.ave been 

 equally effected at the distance of 3,000 feet. This bold experiment saved eight moDtka' 

 labor and $50,000 expense. 



