CRYSTALLIZATION PRODUCED BY VOLTAIC ACTION. 419 



with copper, the solution of the nitrate of barytes is not perceptibly dis- 

 turbed, and the positive end is oxidized. Are we to conclude there- 

 fore that there has been nothing transferred but the oxygen, and that 

 the sulphuric acid has remained in the sulphate ? The answer to this 

 question is to be obtained only by analysing the secondary productions 

 formed in the tubes ; but there is every reason to believe that sulphate 

 of barj'tes Avould be found. In general, when there is one of the pro- 

 ducts of the decomposition not to be found at one of the poles, we may 

 be certain that it has been arrested, on its way, by superior affinities. 



The acetates and subacetates of lead are also decomposed by means 

 of leaden wires ; but the acetate of copper and the saturated solution 

 of the same salt in ammonia resist the action of an electricity of low 

 tension when copper wires are plunged into their solutions. These re- 

 marks are of some importance, inasmuch as these salts are easily de- 

 composable by the ordinary chemical processes. 



Of Electro-chemical Comjjounds or Secondary Productions. 



In stating the phaenomena connected with the decompositions pro- 

 duced by voltaic electricity, we have directed attention to the fact 

 that the results of these decompositions were simple or compound, ac- 

 cording to the nature of the bodies submitted to experiment, and that 

 of the bodies employed as conductors. We have observed, for instance, 

 that in decomposing a solution of sulphuric acid with a piece of char- 

 coal, serving as a positive conductor, we obtained, instead of oxygen, 

 gaseous oxide of carbon and carbonic acid gas, in consequence of the 

 action of the oxygen (which is in its nascent state) upon the charcoal. 

 Other instances of the same kind have been cited in treating of the cha- 

 racters of the bodies developed on the metallic plates, and the definite 

 nature and extent of electro-chemical decomposition. 



We are now about to resume the consideration of this question and 

 carry its solution as far as the present state of science will allow us, in 

 order to show in what manner the chemical action of electricity may be 

 applied in explaining a great number of natural phasnomena which have 

 been hitherto considered independent of this universal agent. 



For a long time no one could conceive how, by means of electric 

 forces, feeble in appearance, powerful affinities were to be overcome, for 

 tiie purpose of decomposing bodies and producing new combinations. It 

 was thought that it would be always necessary to employ currents pos- 

 sessing some degree of energy : but as soon as the electrical effects which 

 take place in chemical actions were analysed, all doubt was removed as 

 to the possibility of attaining the same end by making a proper applica- 

 tion of those effects. It was conceived, in short, that when any voltaic 

 pair is plunged into a solution which acts on one of the elements of that 



