VNI\ 



MAGNETIC PERMEABILITY OF XICKEL AND COBALT 



61 



Up to the present time cnly the rings whose dimensions are given 

 have been used. 



The following Tables from the nickel ring No. I leave little to be 

 desired in point of regularity, and confirm the fact proved in my first 

 paper, that the laws deduced for iron hold also for nickel, and also 

 confirm the value given in my other paper for the maximum value of 

 magnetization of nickel. But the most important thing that they show 

 is the effect of heat upon the magnetization of nickel; and Table III 

 contains the first numerical data yet obtained on the effect of heat on 

 the magnetic properties of any substance. 



As all the rings were wound with two layers of wire, a slight correc- 

 tion was made in the value of S) for the lines of inductive force which 

 passed through the air and not through the metal. In all the experi- 

 ments of this paper greater care was used to obtain T than in the first 

 paper. Each value of >, 33, and T is the mean of four readings. In 

 all the Tables I have left the order of the observations the same as that 

 in which they were made, and have also put down the date, as I now 

 have reason to suspect that the leaving of a ring in the magnetized state 

 in which it is after an experiment will in time affect its properties to a 

 small extent. Let me here remark that the time necessary to simply 

 make the observations is only a Very small fraction of that required to 

 prepare for them and to afterwards discuss them. And this, with the 

 small amount of time at my disposal, will account for the late day at 

 which I publish my results. 



The following is the notation used, the measurements being made on 

 that absolute system in which the metre, gramme, and second are the 

 fundamental units. 



