150 Dr. S. W. Richardson on the Magnetic 



T = 380°C. 



T = 420°C. 



T=440°C. 



H. 



B. 



H. 



B. 



H. 



B. 



6-75 

 4-14 

 173 

 0-72 



218 

 160 

 105 



57 



6-75 

 4-14 

 173 

 0-72 



68 

 50 

 30 

 28 



6-75 

 4-14 

 1-73 

 072 



45 

 30 

 15 

 14 



Alloy No. III. 



The third alloy investigated contained 18*47 per cent, of 

 aluminium. It was exceedingly hard. The molten metal 

 was cast into a disk, and a hole was bored through the central 

 part of this by means of the emery cylinder. The critical 

 temperature was found to be about 25° 0. 



The experiments give no evidence of temperature hys- 

 teresis — the B and T curves obtained with rising temperatures 

 being identical with those obtained with falling temperatures. 



The great similarity between these curves and the latter 

 part of those for Alloy No. II. {e.g. the part above 200° 0.) 

 leads to the conclusion that the maximum value of the 

 induction is probably attained at a temperature much below 

 any reached in the experiments. 



The curves on fig. 19 (p. 153) show that the values of the 

 induction obtained in the experiments on this alloy can, in the 

 main, be relied on to -^ of aline. 



The largest induction observed during the experiments was 

 about 21*5 lines, and the smallest about 2*4 lines. 



The greatest permeability was equal to 3*7. 



As in the case of the other alloys, there is a remanent 

 permeability after the critical temperature is passed ; its 

 value is about 1*5. A curve connecting the temperature and 

 time during cooling did not indicate an evolution of heat on 

 passing the critical point. 



As, however, the cooling took place in the air, the test is 

 not sensitive, and this result cannot be regarded as of much 

 value. 



The temperature of the alloy during the experiments was 

 regulated by the methods 2 and 3 described in § IV< 



Dimensions of Ring. 



External diameter . . . . 6*50 cms. 



Internal „ .... 4*48 „ 



„ thickness . . . . 1*76 „ 



Mean Section 1*78 sq. cms. 



