612 Dr. H. A. Wilson on the Current-Density at 



Table IV. — Aluminium wire, diameter 061 mm. 



p- 



I. 



C. 



• 



C 

 fp- 



8-5 



6-6 



8-83 



0-16 



4-07 



131 



6-92 



0-13 



2-87 



M 



5) 



5-3 



5-55 



2-85 



10-45 



2-30 

 2-36 

 118 

 5-36 



015 

 0-15 

 0-14 

 018 



2-43 



CvCxy 

 5-8 



2-52 

 1-93 



0-16 

 014 



1-94 



10-9 



5-1 

 3-0 



3-29 

 1-35 

 0-81 



0-16 

 014 

 014 



1-38 



4-75 



6-15 



5-85 



10-85 



11-95 



0-67 

 0-97 

 0-98 

 214 

 2-40 



010 

 Oil 

 012 

 014 

 015 



0-94 



74 



9-9 



0-80 

 101 



012 



Oil 



048 



13-9 

 9-4 



0-885 

 0-57 



0-13 

 013 







Mean ... 



0-139 



Table V 



Diameter. 



C 



If 



c c 



Ipnd' lpTr{d-\-0-05)' 



0208 cm. 

 0-142 „ 

 0-061 „ 

 0-019 „ 



0323 

 0-236 

 0139 



088 



0-50 0-403 

 0-53 0-394 

 0-72 0-397 

 1-47 406 



density is the same for all four wires. The results of this 

 calculation are given in the last column of Table V. 



It appears, therefore, that the effective area of a cathode is 

 that of a layer 0'25 mm. thick covering it. At the surface 

 of this layer the current-density is given by the formula 

 i = 0'4p. The above results also show that the current- 

 density is the same for cathodes of platinum as for cathodes 

 of aluminium. 



If we suppose that the current at the cathode is entirely 





