VOLTAIC PHENOMENA. 305 



is called the current of electricity passes, the following question 

 occurred to me in some experiments on the calorific effects of 

 voltaic electricity. If the ignition of a thin wire be the result 

 of a change in the arrangement of its own particles, caused by 

 an antagonist force to that which determines its aggregation, 

 what will be the effect of this force, pushed to the extreme ? 

 e.g. Voltaically ignite a given wire to fusion, arrange it so 

 that after fusion the wire shall retain its position in the 

 voltaic circuit, and what will be the result ? The experiment 

 was tried with platinum and lead wires, placed in a little 

 gutter of unglazed porcelain, which would retain the metal 

 after fusion. The effect upon the platinum wire was as 

 follows : after fusion the wire appeared to swell slightly, and 

 then burst asunder with a snapping noise ; one of the frustra 

 again ignited, again burst, and so on, until the portions 

 became too thick to be fused by the voltaic force employed. 

 The broken ends presented no very remarkable appearance. 

 My deduction from this experiment was, that the voltaic cur- 

 rent tended to expand the wire in the transverse, and to 

 contract it in the longitudinal direction. 



With wires of lead the effects were more remarkable. 

 After fusion this metal evinced a tendency to contract in 

 length ; and, the direction of this contraction being followed 

 by gently approaching the terminal wires, which touched its 

 extremities, it appeared, as it were, to germinate ; it shot out 

 an irregular series of nodules. I may rudely compare the 

 effect to a membranous gullet, tied with a series of ligatures, 

 and then distended to the utmost. Each nodule pressed upon 

 its neighbour and formed dividing facets, which, when cold, 

 could be easily separated by the nail or by a blunt penknife. 



The experiment, when carried on for some time, generally 

 ended either in the breaking asunder of the lead (though, 

 from its want of elasticity, unattended with the snapping 

 noise), or else the circuit was interrupted by the oxidation of 

 the lead. 



