1835.] Philosophical Transactions for 1834. 235 



be chosen from among the metals ; charcoal also answers. No elec- 

 tric current is however induced by these means. An electrolyte is 

 always a compound body, and can act as an electric conductor only 

 when decomposing. Water is the most familiar electrolyte. The 

 attraction of the zinc for the oxygen is greater in the case of water 

 than that of the oxygen for the hydrogen, but in combining with it, 

 it tends to throw into circulation a current of electricity in a certain 

 direction. The sulphuric acid used in the voltaic circuit is not capable 

 of producing any sensible portion of the electricity of the current, 

 by its combination with the oxide formed, because it forms no part 

 of an electrolite, nor is it in relation with any other body present 

 in the solution which will permit of the mutual transfer of the par- 

 ticles, and the consequent conduction of the electricity. Now, an 

 electrolyte conducts in consequence of the mutual action of its 

 particles, but the elements of the water and sulphuric are destitute 

 of this relation. This corroborates the statement of Sir H. Davy, 

 that no electric current is induced by the combination of acids and 

 alkalies. If the acid and base be dissolved in water, it is possible 

 that a small portion of electricity, proceeding from chemical action, 

 may be conducted by the water without decomposition, but the 

 quantity will bear no proportion to the equivalents of chemical force. 

 If a hydrogen acid be used, then a current may be induced by the 

 chemical action of the acid on the base, for both bodies now act as 

 electrolytes. 



This view of the oxidation of the metal being the cause of the elec- 

 tric current, is proved by the effects of alkaline and sulphuretted solu- 

 tions when used as conductors. It cannot be supposed that the alkali 

 acts chemically as an acid to the oxide formed, because our knowledge 

 leads to the conclusion that the ordinary metallic oxides act rather as 

 acids to the alkalies. Ammonia as well as potash produced the same 

 electric currents. Alkalies seem not to be influenced by the acids, in 

 effecting electrical currents, but are superior in force and in bringing 

 a metal into what is called the positive state. It is proved by the 

 fact that if zinc and tin be used, or tin and lead, whatever metal is 

 put into the alkali becomes positive, that in the acid being negative. 

 Davy shewed that if iron and copper were plunged into dilute acid, 

 the current passed from the iron through the fluid to the copper. 

 In the solution of sulphuret of potash it is reversed. Two experi- 

 ments in addition complete the series of proofs of the origin of elec- 

 tricity on the voltaic pile. A fluid amalgam of potassium containing 

 not more than -~ of that metal was put into pure water, and con_ 

 nected through the galvanometer with a plate of platinum in the same 

 water ; a current passed from the amalgam to the platinum, which 

 must have been owing alone to the oxidation. Again, a plate of clean 

 lead and a plate of platinum were placed in pure water, a current 

 passed from the lead to the platinum, so intense as to decompose a 

 solution of the iodide of potassium, when acted upon in the manner 

 described at the beginning of the paper. This likewise appears to 

 have been an instance of the effect of oxidation. 



An important point to determine is the state of the metals and the 

 conductor in a simple circuit, before, and at the instant when the 

 metallic contact is completed. Dr. Faraday conceives it impossible 



