the Galvanic Current through Iron. 



11 



Here S has increased, in comparison with experiment 13, 

 exactly in the ratio of the magnetizing force. 



The following series of experiments were all made with the 

 adiathermanous apparatus. 



With unannealed iron wires the residual effect of the extra 

 currents after the closing of the magnetizing and the principal 

 current is very protracted; so that here we can often only 

 with difficulty separate the transient from the permanent phe- 

 nomena. Hence I designate by w± the resistance in the first 

 period (often amounting to some minutes) after the closing of 

 both currents, by iv 2 the resistance that has become constant. 



16. H = 1D; M = 3B; n=150. Iron wire / 4 (d about 

 0'60). Mean values : — 



Wu + 



w = O79046 

 w 1= 0-79107 

 w 2 =O79052 

 io n =0-79044J 



w-. 



0-0698 

 -w = 0-00061 

 .-w = 0-00007' 



Wr 



__ 



= o 1= +0*00084 



!^z3 = a 2 = + o-oooio. 



Wl.+ 



17. The same repeated. 

 w =0-78998-) 



1^=0-79050 I ^-^=0-00052 

 w 2 =0-79010 f «7 2 -i^=0-00012 



^ =0-78998) 



5 1 = 0*00072 



5 2 = 0*00016. 



Therefore, on the repetition of the experiment, S x has become 

 less, S 2 nas increased. With this agrees the fact that after 

 being used many times wires mostly give no perceptible dif- 

 ference between 8i and S 2 . 



18. H = 1D; M = 3B. Strong iron wire/ 5 (d about 1-3). 



■w =0'16617^ 



w 1= 0-16640 I w 1 -«; = 0-00024 

 w 2 = 0-16630 f w 2 -w = 0-00016 

 w = 0-16613j 



^ = 0-00260 ^ 2 = 000156. 



Here not only are 8 1 and B 2 absolutely greater than in the 

 two preceding series, but S 2 is much greater in comparison 

 with 8 lm There only one fifth part of the initial increase of 

 resistance was permanent; here, more than half. 



w k + 



