1879.] 



The Chloride of Silver Battery. 



285 



surfaces, for which only a few experiments were made, the coincidences 

 were not quite so perfect. Nevertheless, it would appear that the law 

 of the hyperbola holds equally well for a constant pressure and varying 

 distance as it does for a constant distance and varying pressure ; the 

 obstacle in the way of a discharge being up to a certain point as the 

 number of molecules intervening between the terminals.* 



In the two cases of spherical and plane surfaces the ratio between 

 the transverse (distance) and conjugate (potential) axes of the respec- 

 tive hyperbolas was — 



For spherical surfaces . . . . . . 1'240 



„ disks .. .. .. •• 1*285 



With the data already published in Part I, the authors have laid 

 down a fresh curve for the striking distance between flat disks on a 

 scale of 10 centims. for a millimetre and 5 centims. to 1,000 cells. 



From the curve thus laid down the following numbers were 

 deduced :— 



EMF in volts. 



Striking distance 



Difference of 

 potential per 

 centimetre. 



Intensity of force. 



in centimetres. 



Electromagnetic. 











Electrostatic. 







volts. 







1,000 



-0205 



48,770 



4 -88 x 10 12 



163 



2,000 



0-0430 



46,500 



4 -65 „ 



155 



3,000 



-0660 



45,450 



4-55 „ 



152 



4,000 



-0914 



43,770 



4-38 „ 



146 



5,000 



0-1176 



42,510 

 40,740 



4-25 „ 



142 



6,000 

 7,000 



-1473 



4-07 „ 



136 



0-1800 



38,890 



3 "89 „ 



130 



8,000 



-2146 



37,280 



3 -73 „ 



124 



9,000 



0-2495 



36,070 



3 -61 „ 



120 



10,000 



-2863 



34,920 



3-49 „ 



116 



11,000 



-3245 



33,900 



3-39 „ 



113 



11,309 



3378 



33,460 



3'35 „ 



112 



The remainder of the paper is chiefly occupied with the study of 

 the phenomena of the electric arc under various conditions of distance, 

 pressure, and potential; the results obtained support the view that 

 the arc and the stratified discharge are merely modifications of the 

 same phenomenon. 



* Dr. Alexander IVIacfarlane has published in the " Transactions of the Koyal 

 Society of Edinburgh," 1878, vol. xsvii, an elaborate and careful research of the 

 "Disruptive Discbarge of Electricity" in air and different gases, and between 

 terminals of various forms. An abstract of this paper will be found in " ^Nature," 

 December 26, 1878, pp. 184, 185. Dr. Macfarlane used a Holtz machine and 

 employed higher potentials than those we used ; he f ound that the results for the 

 discbarge between two disks 4 inches in diameter at various distances up to 1*2 

 centims. and with various pressures were satisfactorily represented by the hyperbola. 



