1889.] Magnetic Properties of Alloys of Nickel and Iron, 23 



IV. " Magnetic Properties of Alloys of Nickel and Iron." By 

 J. Hopktnson, D.Sc, F.R.S. Received December 2, 1889. ' 



Several alloys have been examined, supplied to me very kindly by 

 Mr. Riley, of the Steel Company of Scotland. I confine myself to a 

 brief statement of the results with the most interesting sample. Mr. 

 Riley informs me that this sample contains 25 per cent, of nickel. 

 As the material was given to me it was non-magnetic at ordinary 

 temperature, that is to say, the permeability was small, about 1*4, 

 and the induction was precisely proportional to the magnetising 

 force. The ring on being heated remained non-magnetic up to 

 700° C. or 800° G. A block of the material did not recalesce on being 

 heated to a high temperature and being allowed to cool. 



On being placed in a freezing mixture bhe material became magnetic 

 at a temperature a little below freezing point. 



The material was next cooled to about —51° C, by means of solid 

 carbonic acid, and the curve of magnetisation was ascertained, as 

 shown in fig. 1, corresponding to a temperature of 13° 0. j from this 

 it will be seen that the ring of the material, which was previously 



Fig. 1. 



