98 SECTION PHYSICS. 



is this : formerly it was a point of doubt whether the spark would 

 jump any appreciable distance before the circuit is closed. We have 

 found the length of the discharge to be in the direct ratio of the square 

 of the number of elements, and that leads to some very curious 

 conclusions. For instance, in the paper, from the Proceedings of the 

 Royal Society r , I have before me the results given as follows : 



Cells. Rod chloride of silver. Striking distance. 



600 '0033 inch. 



1200 -0130 



1800 -0345 



2400 ... -0535 



which is very nearly the square of the number of cells. But as we have 

 carried the number of experiments further we find that the striking dis- 

 tance increases in a far greater ratio. But even if the striking distance 

 does not increase in a greater ratio than that and looking upon 1000 

 cells as unit because with this high intensity we must have a larger 

 unit than one cell if we carry the battery up to 1000 units, or one 

 million cells, the striking distance would be 764 feet, a true flash of 

 lightning not only in distance but in quantity. I think it is not likely 

 that a million cells will ever be made, but it is quite possible to carry 

 up the number to 20,000 or 30,000 cells, and it is almost impossible to 

 foresee the results one will obtain as the number increases. The 

 advantage of this battery is that one can have it in one's laboratory 

 always ready, walk in and make experiments at any time. Most 

 other batteries from efflorescence or other causes continually get out 

 of order, but with this one the first thousand was charged up in 

 November, 1874, and to-day I was working with it and had the 

 honour of showing some experiments to some of our foreign visitors. 

 The acting electrolyte is the solid chloride of silver, which is insoluble 

 in the weak solution of chloride of ammonium, with which the cells are 

 charged, and yields up its chlorine only when the circuit is closed ; at 

 other times no action takes place, and consequently no consumption 

 of material occurs ; indeed, the battery remains always in action, 

 and is very nearly constant. You notice figure 2 that the stoppers 

 are made with paraffin, the feet are of ebonite, and the connectors 

 are mounted on ebonite, so that the insulation is very perfect, and 

 very little leakage takes place. It is most agreeable to be able to 



