Brown — Chrome Steel Permanent Magnets. 



353 



To check the point on the curve corresponding to dimension-ratio 100, 

 five magnets were made of the same wire, each 10 cm. long ; and tlie mean 

 of the magnetic moments gave the value 65-1. There was no perceptible 

 loss in the moment wlien these magnets were let fall end on four times 

 through a height of one metre on to the glass block. 



To show that the magnetic moment per gramme varies with the form of 

 the sample tested, the values obtained by different observers for chrome 

 steels (other than those in Table I.) have been brought together in Table II., 

 in which the percentages of carbon and chromium only are given. 



Table II. 



Comparing the values of the magnetic moments for the last two specimens 

 in tliis Table with the values for Nos. 4 and 6 in Table I., which have 

 approximately the same amounts of chromium, we find that the magnetic 

 moments are less by about 1 3 and 28 per cent, respectively. This is, no 

 doubt, due to the presence of manganese in Nos. 4 and 6. Tlie chemical 

 compositions of the last two specimens in Table II. are not known beyond 

 the amounts of carbon, chromium, and iron. 



SOIENT. PEOC. B.D.S., VOL. XH., NO. XXIX. 



3 m 



