320 Royal Institution. 



being capable by its fall of producing electricity or other force, force 

 would not thus be got out of nothing, or perpetual motion attained. 



The experiment is believed to be new, and to be suggestive of 

 others of a similar character, which may be indefinitely varied*. 

 Thus, two balls made to diverge by electricity should not give to 

 an electrometer the same amount of electricity as if they were, 

 ■whilst electrified, kept forcibly together, an experiment which may 

 be tried bj' Coulomb's torsion balance. 



There is an advantage in electrical experiments of this class, as 

 compared with those on heat, viz. that though there is no perfect 

 insulation for electricity, yet our means of insulation are immeasu- 

 rably superior to any attainable for heat. 



Similar reasoning might be applied to other forces ; and many 

 cases bearing on this subject, have been considered by Mr. Grove 

 in his essay on the " Correlation of Physical Forces." 



Certain objections to these views were then discussed, and espe- 

 cially some apparently formidable ones presented by M. Matteucci 

 in a paper published by him some time agof. 



This distinguished philosopher cites the fact, that a voltaic 

 battery decomposing water in a voltameter, while the same current 

 is employed at the same time to make an electro-magnet, never- 

 theless gives in the voltameter an equivalent of gas, or decomposed 

 substance, for each equivalent of chemical decomposition in the cells, 

 and will give the same ratios if the electro-magnet be removed. 

 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 force 

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

 meter. If, moreover, the magnet is not interposed, still the magnetic 

 force is equally existent through the whole circuit; for instance, the 

 wires joining the plates will attract iron filings, deflect magnetic 

 needles, &c. By the iron core a small portion of the force is 

 absorbed while it is being made a magnet, but this ceases to be 

 absorbed when the magnet is made ; this is proved by the recent 

 observations of Mr. Latimer Clarke, which were fully entered into 

 and extended by Mr. Faraday, in a lecture at the Institution 

 (Jan. 20, 1854 X). It is hke the case of a pulley and weight, which 

 latter exhausts force while it is being raised, Ijut 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 preponderating chemical 

 affinity in the battery cells, either by the nature of its elements or 

 by the reduplication of series, to effect decomposition in the vol- 

 tameter, 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 



* See some observations on this experiment in our last Number, \i. 225. 

 t Archives des Sciences Physiques, vol. iv. p. 380. 

 X Phil. Mug. vol. vii. p 197. 



