26 ELECTROLYSIS. 



By expending a work of 1092800 kilogrammetres it would 

 therefore be possible to obtain a chemical energy capable of 

 producing 1623708 kilogrammetres ; this would involve the 

 creation of a certain quantity of energy, which is impossible. 



If we admit that the quantity of decomposed water is pro- 

 portional to the work of dissociation, we find that to equilibrate 

 the work of recomposition equal to the electro-chemical equiva- 

 lent of water 



" O' 0000000627 kilogramme. 



28708 



So that one ampere, which ought to decompose 09328 milli- 

 gramme of water, would only decompose 0627 milligramme ; 

 this is contrary to Faraday's law. 



Thus to explain the decomposition of water by means of a cur- 

 rent of an electromotive force of one volt, there would only remain 

 the supposition that the oxygen and hydrogen obtained possess 

 other properties of combination than those which these gases 

 generally have, or, in other terms, would imply that 8 grammes 

 of oxygen, when burning one gramme of hydrogen, produce 

 22 calories, instead of 34*5, which is absolutely incorrect. 



We can therefore affirm that it is impossible to electrolyse 

 water with an electromotive force inferior to 1 495 volt. An 

 electromotive force superior to 1 495 volt will even be required for 

 overcoming the resistances of the conductors and of the bath, 

 which resistances can never be completely done away with. 



Quite recently M. Tommasi professed to be able to decom- 

 pose water with a single cell of zinc-carbon or zinc-copper, with 

 dilute sulphuric acid ; but in order to obtain this result, he made 

 use of suitable electrodes. For instance, when using copper or 

 zinc as anode and platinum as cathode, he very rapidly decom- 

 posed water with a single zinc-carbon cell; and when using a 

 platinum anode and a copper cathode he equally obtained a 

 rapid decomposition with a single zinc-copper cell. In these 

 decompositions hydrogen only would be given off, oxygen 

 becoming combined with the positive electrode. 



After a long series of experiments, M. Tommasi concluded 

 as follows : 1. One single zinc-copper or zinc-carbon cell, 



