1856.] the Negation of Perpetual Motion. 137 



This experiment has succeeded in so large an average of cases, 

 and so responds to theory, that, notwithstanding the imperfection of 

 the apparatus, Mr. Grove places much reliance on it ; indeed, it is 

 difficult to see, if the discharges or other electrical effects were the 

 same in both cases, why the raising the ball, being extra, and the 

 ball 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 by 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 immeasur- 

 ably 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 ago.* 



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 ab- 

 sorbed 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, 1854t). 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. 



* Archives des Sciences Physiques, Vol. IV., p. 380. 

 t Proceedings of the Royal Institution, Vol. I., p. 345. 



