1 64 CORRELATION OF PHYSICAL FORCES. 



first sight, it would appear that the magnetism was an extra 

 force produced, and that thus more than the equivalent power 

 was obtained from the battery. In answer to this objection 

 it may be said, that in the circumstances under which this 

 experiment is ordinarily performed, several cells of the battery 

 are used, and so there is a far greater amount of heat, &c., 

 generated in the cells than is indicated by the effect in the 

 voltameter. If, moreover, the magnet be not interposed, still 

 the magnetic force is equally existent throughout the whole 

 current; for instance, the wires joining the plates will attract 

 iron filings, deflect magnetic needles, &c v and produce 

 diamagnetic effects on surrounding matter. By the iron core 

 a small portion of the force is, indeed, absorbed while it is 

 being made a magnet, and probably less heat is developed in 

 the circuit, but this ceases to be absorbed when the magnet 

 is made; this has been proved by the observation of Mr. 

 Latimer Clarke, who has found that along the wires of the 

 electric telegraph the magnetic needles placed at different 

 stations remained fixed after the connection with the battery 

 was made, and while the electric current acted by induction 

 on surrounding conducting matter, separated from the wires 

 by their gutta-percha coating, so that a sort of Leyden phial 

 was formed ; but as soon as this induction had produced its 

 effect between each station, or, so to speak, the phial was 

 charged, the needles successively were deflected : it is like the 

 case of a pulley and weight, which latter exhausts force while 

 it is being raised ; but when raised, the force is free, and may 

 be used for other purposes. 



If a battery of one cell, just capable of decomposing 

 water and no more, be employed, this will cease to decompose 

 while making a magnet. There must, in every case, be pre- 

 ponderating chemical affinity in the battery cells, either by 

 the nature of its elements or by the reduplication in series, to 

 effect decomposition in the voltameter; and if the point is 

 just reached at which this is effected, and the power is then 

 reduced by any resistance, decomposition ceases : were it 

 otherwise, were the decomposition in the voltameter the ex- 

 ponent of the entire force of the generating cells, and these 

 could independently produce magnetic force, this latter force 

 would be got from nothing, and perpetual motion be obtained. 



