1881.] 



On a New Electrical Storage Battery. 



189 



gamated thoroughly with mercury, and a sheet of thin copper a little 

 shorter ; the two sheets are perforated with a number of holes and 

 then rolled in a spiral, separated by rubber bands cut every five 

 inches, the holes in plates and cuts in rubber bands being to allow 

 free circulation of the solution (the short plate being uppermost 

 before rolling). This combination is immersed in a solution of cupric 

 sulphate, and the amalgamated lead plate made the positive electrode 

 of a suitable source of electricity, the chemical action being that the 

 oxygen of the decomposed solution combines with the lead, forming a 

 perfectly even coating of the insoluble peroxide, the hydrogen re- 

 placing the copper of the solution, and the copper being deposited in 

 the metallic state on the negative electrode. As the decomposition of 

 the cupric sulphate proceeds the solution gradually loses its azure blue 

 colour, becoming more acid, and finally when the whole of the copper is 

 deposited, we have the solution colourless and transformed into hydric 

 sulphate and water, the positive electrode peroxidised and copper 

 deposited on the negative electrode. During discharge the peroxide is 

 reduced and the copper element oxidised, the oxide combining with 

 the acid and forming cupric sulphate, the solution returning to its 

 original colour. This change of colour forms a beautiful means of 

 telling when the cell is charged ; it is a veritable charging gauge. 

 The power of this cell is very great and very constant, it can be made 

 to last for hours, the time being dependent on the quantity of cupric 

 sulphate decomposed. 



I have, by the decomposition and recomposition of one pint of 

 cupric sulphate, obtained over two hours' effective work in heating to 

 a red heat one inch of No. 28 iron wire, the cell measuring internally 

 4 inches deep and 4 inches diameter. 



I constructed cells with free crystals of cupric sulphate suspended 

 in the solution, and found that the presence of free crystals prevented 

 the oxidation of the amalgamated lead electrode, it being essential 

 that the solution become slightly acid before the peroxide will form. 

 The cell during charging gives out a peculiar rattling noise, which I 

 consider due to the deposition of copper on the negative electrode 

 altering the form of the spiral. 



A practical form of cell for storing purposes ought to be made, by 

 fixing a series of amalgamated lead piates in a box in grooves, as in 

 Cruikshank's trough battery, filling the interval between the plates 

 with solution of cupric sulphate, and passing a current through of 

 sufficient tension to overcome the contrary electromotive force of the 

 series, the positive sides of the plates being peroxidised and copper 

 deposited on the negative sides. I have two boxes on this plan, each 

 containing twenty-five plates, the total being equivalent to fifty cells. 

 By this means batteries of great tension can be charged from thirty 

 Bunsens. A number of twenty-five plate boxes can be coupled for 



