324 



On the Chloride-of- Silver Battery. 



[June 14, 



VIII. c< On the Length of the Spark between two Spherical Sur- 

 faces of the Chloride-of- Silver Battery." By Warren De La 

 Rue, M.A., D.C.L., F.R.S., and Hugo W. Muller, Ph.D., 

 F.R.S. Received June 14, 1877. 



In anticipation of a detailed account of our researches in voltaic elec- 

 tricity, which have engaged our attention for nearly three years, we ven- 

 ture to publish, as of interest to the electrician, an account of the results 

 obtained with two spherical surfaces of 3 inches radius and 1*5 inch 

 diameter. It will be seen that they differ materially from those which 

 occur from the employment of a point for one terminal and a flat disk for 

 the other, with which the striking-distance is in the ratio of the square 

 of the number of cells up to 8040, as has already been stated to be the 

 case up to 2400 cells (Proc. Roy. Soc. no. 166, 1876). 



The Ag CI cell is taken as equal to 1*03 volt in the calculations from 

 which the following numbers are derived : — 



Difference of Length of spark in 



potential 



air at the atmo- 



in volts. 



spheric pressure. 





in. 



250 



o-ooioo } 



500 



0-00225 \ 



750 



0-00350 J 



1000 



0-00482 ) 



1500 



0-00820/ 



2000 



0-01233 \ 



2500 



0-01700/ 



3000 



0-02200 \ 



3500 



0-02700 j 



4000 



0-03225 \ 



4500 



0-03775 j 



5000 



0-04325 1 



5500 



0-04900 / 



6000 



0-05460 1 



6500 



0-06070/ 



7000 



0-06650 1 



7500 



0-07250 I 



8000 



0-07850 J 



Additional length of spark for 

 1000 additional volts. 



in. 



ween and 1000 0*00482 



„ 1000 „ 2000 0-00751 



„ 2000 „ 3000 0-00967 



„ 3000 „ 4000 01025 



„ 4000 „ 5000 0-01100 



„ 5000 „ 6000 0-01135 



„ 6000 „ 7000 0-01190 



„ 7000 „ 8000 ...... 0-01200 



It is evident that, for small distances between the terminals, a higher 

 difference of potential is necessary to cause the spark to jump than 

 when they are at greater distance. This agrees with Sir William Thom- 

 son's experience. 



We avail ourselves of this opportunity to state that, when observed 

 with the microscope, the voltaic arc, at ordinary atmospheric pressures, is 

 seen to be stratified, though with some difficulty. 



