Annealing on the Magnetic Moments of Steel Magnets. 421 



The proportions are on this account probably only roughly 

 approximate, and until special analyses are obtained it seems 

 unnecessary to give the actual quantities. 



Table I. 

 Comparative Composition of the Specimens. 



Substance. 



Number of specimen. 



I. 



II. 



III. 



Silicon 



Manganese 



1-00 

 1-00 

 100 



1:00 



100 

 100 



0-08 

 1-23 

 1-71 

 000 

 0-25 

 0-994 



017 

 3-25 

 1-55 



o-oo 



0-25 



0-987 



Phosphorus 



Sulphur 



Carbon 







All the specimens contain, as a matter of course, nearly the 

 same amount of iron, but the other constituents differ con- 

 siderably. The magnets were prepared in the same manner 

 as those referred to in Part I. of this paper. They were all 

 made glass-hard to begin with ; and this was done by bringing 

 them to a bright red heat, and then dropping them, with their 

 lengths vertical, into a vessel 60 centim. deep, which was filled 

 with water at a temperature of 7° C. 



A greater number of magnets than were actually required 

 were prepared, but only those which were found to be straight 

 and of uniform glass-hardness throughout, chosen for the ex- 

 periments. The hardness was tested by means of a file run 

 longitudinally along and around the magnet ; in this way any 

 marked divergence from uniformity in hardness was detected. 



Also, to make sure that all the pieces of the same sample 

 should be as nearly as possible alike, they were one by one 

 let fall on to a block of hard wood, and those which gave the 

 same kind of metallic ring were taken for the experiments. 

 They were then thoroughly cleaned and polished, and their 

 lengths, diameters, and weights accurately determined ; these 

 measurements being, for ease of reference, given below in 

 Table II. 



There were fifteen magnets in all, i. e. five samples of each 

 specimen, and each one was made exactly 10 centimetres in 

 length, 



