338 Dr. Faradjiy'b Experimental Researches in Electricity, 



tina plate which is associated with it for the purpose of form- 

 ing a voltaic apparatus. 



999. All these evils are removed by the employment of an 

 amalgam of zinc in the manner recommended by Mr. Kemp*, 

 or the use of the amalgamated zinc plates of Mr. Sturgeon 

 (863.), who has himself suggested and objected to their appli- 

 cation in galvanic batteries ; for he says, " Were it not on ac- 

 count of the brittleness and other inconveniences occasioned 

 by the incorporation of the mercury with the zinc, amalgama- 

 tion of the zinc surfaces in galvanic batteries would become 

 an important improvement ; for the metal would last much 

 longer, and remain bright for a considerable time, even for 

 several successive hours ; essential considerations in the em- 

 ployment of this apparatusf." 



1000. Zinc so prepared, even though impure, does not 

 sensibly decompose the water of dilute sulphuric acid, but 

 still has such affinity for the oxygen, that the moment a metal 

 which, like copper or platina, has little or no affinity, touches 

 it in the acid, action ensues, and a powerful and abundant 

 electric current is produced. It is probable that the mercury 

 acts by bringing the surface, in consequence of its fluidity, into 

 one uniform condition, and preventing those differences in 

 character between one spot and another which are necessary 

 for the formation of the minute voltaic circuits referred to 

 (998.). If any difference does exist at the first moment, with 

 regard to the proportion of zinc and mercury, at one spot on 

 the surface^ as compared with another, that spot having the 

 least mercury is first acted on, and, by solution of the zinc, is 

 soon placed in the same condition as the other parts, and the 

 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 equa- 

 ble condition (94?9.), which, though it tends to produce an 

 electric current 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 im- 

 portant consequences follow upon this state of the metal. The 

 first is, that \k\Qfull equivalent of electricity is obtained for the 

 oxidation of a certain quantity of zinc ; the second, that a bat- 

 tery constructed with the zinc so prepared, and charged with 



♦ Jameson's Edinburgh Journal, October 1828. 



t Recent Experimental Researches, p. 42, &c. Mr. Sturgeon is of 

 course unaware of the definite production of electricity by chemical ac- 

 tion, and is in fact quoting the experiment as the strongest argument 

 against the chemical theory of galvanism. 



