ELECTR1CITV. 



511 



melted in this manner, sparks are frequently seen at con- 

 siderable distance from it, which are red hot particles of 

 the metal, that by the violence of the explosion, are 

 thrown in all directions. If the force of the battery be 

 very great, the wire will be entirely dispersed by the ex- 

 plosion so that none of it can afterwards be found.' 



By repeating this experiment with wires of different 

 metals, and using the same quantity of electrical power, 

 that is, by using the same battery and charging it to the 

 same degree of intensity, it will be found that some me- 

 tals are fused more readily than others, whilst some are 

 not sensibly affected. This shows the difference of their 

 conducting powers. Some are melted instantaneously 

 through their whole length, and entirely dispersed by the 

 force of the explosion. Others merely melt and drop in 

 globules. Others still, become red hot or are even 

 only heated at the ends. An electrician once had a 

 number of wires prepared of various metals, all of the 

 same diameter, one thirtysecond of an inch. He used a 

 very large electrical machine, to which was attached a 

 battery containing 225 feet of coated surface. The wires 

 were of equal lengths, and the battery charged to the 

 same degree of intensity in all the experiments. The 

 following was the result. Of the leaden wire 120 inches 

 were melted ; of fin the same. Iron wire only five in- 

 ches; gold wire three inches and a half. Silver, cop- 

 per and brass wire, only one quarter of an inch. 



Some writers on electricity have considered these ex- 

 periments as showing directly the conducting powers of 

 these metals, - supposing them to be inversely as the 

 fusibility. It seem more probable that the conducting 

 power is inversely as the heat produced, and as it re- 

 quires much less heat to fuse lead than brass, the lead, 

 even if an equally good conductor, would be much more 

 easily fused. 



The philosopher above alluded to, had the curiosity to 

 try the experiment of fusing these metals under water, 

 and the plan succeeded. It was necessary, however, 

 to use much shorter wires. The same discharge would 

 generally melt one eighth part as much wire under water, 

 as in the open air. 



