18 ELECTROLYSIS. 



order to decompose one equivalent of any given substance, for 

 instance, one gramme of hydrogen, a constant quantity of 

 electricity is required, which may be called electro-chemical 

 equivalents. 



Second law. When the same current simultaneously acts on 

 a series of solutions, the weights of the constituents separated 

 in each of them are in the same ratio as their chemical 

 equivalents. Supposing, for instance, that the current is made 

 to traverse three vats containing, the first some water, the 

 second some nitrate of copper, and the third some nitrate of 

 silver ; for each gramme of hydrogen set free in the first vat 

 will be found, in the second bath 31'75 grammes of copper, 

 and in the third 108 grammes of silver; the figures 1, 31*75, 

 and 108 being respectively the equivalents of hydrogen, copper, 

 and silver. This second law clearly shows that the electric 

 intensity is the same in every point of the circuit whatever 

 may be the nature and the number of successive conductors of 

 which the said circuit is composed. If a series of water volta- 

 meters of widely varying dimensions are placed in the same 

 circuit, it is found that the quantities of hydrogen and oxygen 

 liberated are the same in all the voltameters, although the 

 degree of acidity and of conductibility of the water might have 

 varied in each voltameter.* 



Third law. The electrolytic action is independent of the 

 respective position of the battery and of the electrolyte. This 

 law is easy of demonstration, as it will be found that wherever 

 the battery is placed, that is to say, whether in the bath itself 

 or at a great distance from it, the quantity of electrolyte de- 

 composed does not vary, the conditions of the current remaining, 

 of course, the same. 



Fourth law. The number of equivalents of zinc dissolved 

 in each cell of the battery, is equal to the number of equiva- 

 lents of metal liberated in each electrolyte which is part of the 



* In the application of the voltameter for the measure of feeble currents it must 

 be observed that the quantities of gas liberated in one apparatus, owing to the 

 decomposition of water, do not depend only on the initial intensity of the cur- 

 rent, but also on the degree of acidity of the water, the nature and dimensions 

 of electrodes, the distance between the anode and cathode ; these various causes 

 creating some resistances of a greater or lesser magnitude, and reducing the initial 

 intensity of the current. 



