2 Peirce — Magnetic Properties at High Excitations. 



phorus, less than 0*03 per cent of silicon, and less than 0*003 

 per cent of sulphur. The iron dissolved violently in slightly 

 diluted HN0 3 , and when the residue had been dissolved for 

 carbon, a mere discoloration of the beaker remained. 



There was nothing, therefore, in the composition of the iron 

 core to account for the comparative uselessness of the magnet. 



Fig. 1. 



The response of this remarkable iron to magnetic excitation 

 was equally satisfactory, and the present report describes 

 briefly determinations of the permeabilities of two pieces of it 

 under very strong magnetizing fields. The work was done by 

 Mr. John Coulson and myself, and was extremely troublesome 

 because only a short stout piece of the iron used in making 

 the core was available. From this a rod 1"26 centimeters in 

 diameter and about 30 centimeters long was turned by Mr. 



