458 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. 



whole plate rendered superficially uniform. One part cannot, therefore, act as a 

 discharger to another ; and hence all the chemical power upon the water at its surface 

 is in that equable condition (949.), which, though it tends to produce an electric cur- 

 rent through the liquid to another plate of metal which can act as a discharger (950.), 

 presents no irregularities by which any one part, having weaker affinities for oxygen, 

 can act as a discharger to another. Two excellent and important consequences fol- 

 low upon this state of the metal. The first is, that the full equivalent of electricity is 

 obtained for the oxidation of a certain quantity of zinc ; the second, that a battery 

 constructed with the zinc so prepared, and charged with dilute sulphuric acid, is 

 active only whilst the electrodes are connected, and ceases to act or be acted upon 

 by the acid the instant the communication is broken. 



1001. I have had a small battery often pairs of plates thus constructed, and am 

 convinced that arrangements of this kind will be very important, especially in the 

 development and illustration of the philosophical principles of the instrument. The 

 metals I have used are amalgamated zinc and platina, connected together by being 

 soldered to platina wires, the whole apparatus having the form of the couronne 

 des tasses. The liquid used was dilute sulphuric acid of sp. gr. r25. No action 

 took place upon the metals except when the electrodes were in communication, and 

 then the action upon the zinc was only in proportion to the decomposition in the 

 experimental cell ; for when the current was retarded there, it was retarded also in 

 the battery, and no waste of the powers of the metal was incurred. 



1002. In consequence of this circumstance, the acid in the cells remained active 

 for a very much longer time than usual. In fact, time did not tend to lower it in 

 any sensible degree ; for whilst the metal was preserved to be acted upon at the 

 proper moment, the acid also was preserved almost at its first strength. Hence a 

 constancy of action far beyond what can be obtained with the use of common zinc. 



1003. Another excellent consequence was the renewal, during the interval of rest, 

 between two experiments of the first and most efficient state. When an amalgamated 

 zinc and a platina plate, immersed in dilute sulphuric acid, are first connected, the 

 current is very powerful, but instantly sinks very much in force, and in some cases 

 actually falls to only an eighth or a tenth of that first produced (1036.). This is due 

 to the acid which is in contact with the zinc becoming neutralized by the oxide 

 formed ; the continued quick oxidation of the metal being thus prevented. With 

 ordinary zinc, the evolution of gas at its surface tends to mingle all the liquid toge- 

 ther, and thus bring fresh acid against the metal, by which the oxide formed there 

 can be removed. With the amalgamated zinc battery, at every cessation of the cur- 

 rent, the saline solution against the zinc is gradually diffused amongst the rest of 

 the liquid ; and upon the renewal of the contact with the electrodes, the zinc plates 

 are found most favourably circumstanced for the production of a ready and powerful 

 current. 



1004. It might at first be imagined that amalgamated zinc would be much inferior 



