CHEMICAL AFFINITY. 147 



What the exact nature of the transferrence of chemical 

 power across an electrolyte is, we at present know not, nor 

 can we form any more definite idea of it than that given by 

 the theory of Grotthus. We have no knowledge as to the exact 

 nature of any mode of chemical action, and, for the present, 

 must leave it as an obscure action of force, of which future 

 researches may simplify our apprehensions. 



We have seen that an equivalent or proportionate elec- 

 trical effect is produced by a given amount of chemical action ; 

 if we, in turn, produce heat, magnetism, and motion by the 

 electricity resulting from chemical action, we shall be able to 

 measure these forces far more accurately than when they are 

 directly produced, and thus to deduce their equivalent relation 

 to the initial chemical action. Thus, M. Favre, after ascertain- 

 ing the quantity of heat produced by the oxidation of a given 

 quantity of zinc, and finding, as have others, that the heat 

 so produced is the same in amount as when evolved from a 

 voltaic battery by the same consumption of zinc forming its 

 positive element, makes the following experiment. 



A voltaic battery and electro-magnet are immersed in ca- 

 lorimeters, and the heat produced when the connection with 

 the magnet is effected is noted. 



The electro-magnet is then made to raise a weight, and 

 thus perform mechanical work ; and the heat produced is 

 again noted. It is found in the latter case that less heat is 

 evolved than in the former ; a certain quantity of heat has 

 therefore been replaced by the mechanical work ; and by 

 estimating the amount of heat subtracted, and the amount of 

 work produced, he deduces the relative equivalent of work to 

 heat. These experiments give a production of mechanical 

 work by chemical action, not, it is true, a direct production, 

 but, as the heat and work are in inverse ratios, and each has 

 its source in chemical action, they prove that they are definite 

 for a definite amount of chemical action ; and as each is pro- 

 duced respectively by electricity and magnetism, these forces 

 must also bear a definite relation to the initial chemical force. 



The doctrine of definite combining proportions, which so 

 beautifully serves to relate chemistry to voltaic electricity, led 

 to the atomic theory, which, though adopted in its universality 



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