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XXXVII. On some Experiments with Alternating Currents. 

 By A. Sadowsky, University Professor in Turiew (Dorpat) , 

 Russia*. 



To the Editors of the Philosophical Magazine* 



Gentlemen, 



IN No. 238 (vol. xxxix. 1895) of your valuable Magazine 

 Mr. Griffiths has published a paper on " Some Experi- 

 ments with Alternating Currents," in which he describes 

 some experiments with Lenard's bismuth spiral. I was inves- 

 tigating the same subject in 1892-1893, and obtained the 

 following results, ao-reeing well with those of Mr. Griffiths. 



(1) With the bismuth spiral in a strong field absolute 

 silence in the telephone is never obtained, but only a minimum 

 of sound. 



(2) The superficial distribution of alternating currents is 

 without influence on the resistance. 



(3) The resistance of bismuth depends on the phase of the 

 current. 



The following results are similar to those of Mr. Griffiths, 

 but do not coincide with them in every respect: — 



(1) The bismuth spirals have something like the self- 

 induction, but not equivalent to it; I have tried the hypothesis 



/ , X di\ 



where r is the resistance for a constant current, 

 i the current, 



A, a constant positive coefficient, and 

 r apparent resistance (measured with a Wheatstone 

 bridge and telephone). 

 Under this hypothesis r must be always >r , which does 

 not agree with the experiments of Lenard, Zahn, and myself. 

 (2) I have observed the difference of resistance with fre- 

 quency 500 without field to be as stated by Messrs. Lenard 

 and Zahn; the resistance with a constant current was greater 

 (0*1 per cent.). 



In addition to the above, I have found the following : — 

 (J ) M. Lenard - ' s statement that the difference of resistance 

 is due to the currents of great frequency, i. e. 10,000, is 

 erroneous. Let ordinates of the curve A B C D represent the 



* Abstract of a paper published in the Journal of the Russian Plrvsico- 

 Chemical Society, vol. xxvi. pp. 81-156 (1894). 



