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but not of propagating chemical action, such as unoxidable metals, 

 the circulation of the current was altogether destroyed. 



Since the chemical changes always tend to restore the equilibrium 

 destroyed by the contact of the metals in the fluids of a pile, it is 

 evident that the relation between the fluids themselves and the sur- 

 faces with which they are in contact, will be altered by a continuance 

 of the action of the pile. Hence it is easy to perceive the possibility 

 of a re-action taking place, when the circuit is broken, or the dispo- 

 sition of the parts of a pile is changed, or one or more parts of a 

 compound circuit abstracted. Many curious phenomena, of which 

 hitherto no explanation has been offered, may be explained by this 

 view of the subject ; such as the secondary piles of M. Ritter ; the 

 supposed polarization of electricity concluded by M. De la Rive from 

 his experiments of the interposition of metallic plates in the fluids of 

 a pile ; the continuance of electro-motive action of detached portions 

 of a circuit, after the destruction of the circuit itself, in some expe- 

 riments, &c. This re-action is illustrated in the paper before us by 

 an experiment, in which a circuit, primarily inactive, consisting of 

 six arcs of platinum in vessels filled with solution of nitre, was made 

 part of a battery, consisting of fifty pairs of plates, of a combination 

 primarily active. After continuing the circuit some time it was 

 broken, and the platinum arcs detached and formed into a circuit 

 were found to possess independent action, contrary to that of the 

 pile, which had thus rendered them re-active. This singular conse- 

 quence is pursued yet further in another experiment here stated, in 

 which detached portions of a battery of fifty plates, which had been 

 some time in action, were examined as separate piles, after breaking 

 up the combination. When they had been placed conformably in 

 the original battery, their independent action was found to be very 

 much weakened by the re-action thus produced, which in this case 

 opposed their natural effect ; whereas, when unconformably placed in 

 the original battery, their action, when detached, was found exalted 

 to three or four times its natural intensity. 



The author next proceeds to point out some general observations 

 and practical applications which suggest themselves on a view of the 

 foregoing results. The chemical changes in a conducting liquid, he 

 first shows, take place only in the immediate vicinity of the im- 

 mersed poles, the rest of the liquid affording only a tranquil passage 

 to the electricity. This leads him to consider the motions produced 

 in mercury when interposed in the circuit under an electrified fluid, 

 which he regards as arising from the two electricities acting as 

 transporters of ponderable matters, which assume their own peculiar 

 characters when they reach their point of rest. The lecture con- 

 cludes with some practical suggestions as to the use of the multiplier 

 to obtain exact numerical measures of the electro-dynamic relations 

 of chemical elements, and with some applications of the preceding 

 results to the useful arts, especially in the preservation of the copper 

 on ships, and the iron boilers of steam-engines. 



