100 MR. S. W. J. SMITH ON THE THERMOMAGNETIC ANALYSIS OF 
Fig. 28. Meteoric iron. 
Permeability changes produced by repeated heating. 
of the 2nd winding stated on p. 39. The greater distance of the lower dotted curve 
below the lower full curve at the air temperature than at temperatures above 350° C. ; 
the greater permeability at temperatures above 100° C. on the upper dotted curve 
than on the upper full curve, and the greater permeability above 500° C. on the full 
curve than on the dotted curve, are all in accord with the interpretation given of the 
gradual change of the taenite produced by repeated heating. 
§11. There is only one further point with respect to the curves for the meteoric 
iron that remains to be discussed, viz., the cause of the fact that the 27 per cent, 
irreversible alloy does not become magnetic at the normal temperature, for such an 
alloy, during the first cooling from 800° C. 
It is probable (Section VI., § 5, p. 86) that an irreversible alloy containing only 
6 per cent, of Ni is not completely transformed into the magnetic state during cooling 
until its temperature is near that of the air. The transformation is accompanied by 
considerable increase in volume. Hence, since the later stages take place at a low 
temperature, when the rigidity of the material is comparatively great, a considerable 
