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XC. On Voltaic Electricift/, and on the effects of a Battery 

 charged with Sulphate of Copper. By Mr. W. De la Rue*. 

 T^HE greatest effect being always produced in those voltaic 

 -*■ arrangements where the chemical agent exerted an ac- 

 tion on only one of the metals constituting the battery, it oc- 

 curred to me to use a saturated and perfectly neutral solution 

 of the electro-negative metal, provided the other was capable of 

 effecting its decomposition. I therefore trieil the effect of a sa- 

 turated solution of sulphate of copperf in an elementary voltaic 

 battei'y of the ordinary construction. The zinc plate was four 

 inches by two, the copper completely surrounding it : with this 

 I was enabled to produce ignition of half an inch of platina 

 wire one thirtieth of an inch in diameter, and continue it as 

 long as the zinc plate lasted, which, being very thin, was dis- 

 solved in a couple of hours. The effects of this battery were 

 considerably greater than those of one made of platina and 

 zinc of the same dimensions, this being immersed in diluted 

 nitric acid. 



I afterwards constructed a battery with three four-inch zinc 

 plates connected together; these were immersed in a copper 

 trough with two partitions, so that the zinc should be opposed 

 on both its surfaces to a plate of copper : with this battery one 

 inch of fine iron wire was kept ignited for four hours. The 

 zinc plate is always partially covered with a coating of copper, 

 •which, howevei; is not detrimental to the power of the battery : 

 the copper plate is also covered with a coating of metallic 

 copper, which is continually being deposited; and so perfect is 

 the sheet of copper thus formed, that, on being stripped off], 

 it has the polish and even a counterpart of every scratch of 

 the plate on which it is deposited. Besides this, the voltaic 

 influence decomposes the water; the oxygen, uniting with a 

 portion of the copper and hydrogen, being set at liberty. This 

 may be readily shown by soldering at one end a piece of copper 



• Communicated by the Author. 



f Daniell uses sulphate of copper, but not as the exciting agent. 



[Professor Daniell's object was to obtain a voltaic combination constant 

 in its effects while the connexion is completed, and totally inactive when 

 the circuit is interrupted. Suljjliate of copper, used as an exciting agent, 

 he found unsuited for this purpose, and therefore relinquished this employ- 

 ment of it in his battery. That it did not escape Prof. D.'s attention, the 

 following passage from his paper on Voltaic Combinations, in the first 

 part of the Phil. Trans, for 1836, page 117, will show: "Upon adding 

 sulphate of copper, in any considerable quantity, to the liquid in the cells, 

 notwithstanding the amalgamation of the zinc, there was local action enough 

 upon that metal to disengage hydrogen, which, in however small a quan- 

 tity, was sufficient to commence the precipitation of the copper upon it. 

 Single circles were thus immediately formed by the two metals, and local 

 action increased to such a degree as speedily to cover the zinc with reduced 

 copper." See also page 1 09 - Edit.] 



