32 
Proceedings of the Royal Society of Edinburgh. [Sess. 
this greater vibrational intensity, a larger proportion of the molecules must 
tend to rotate negatively, and this could be accomplished by a further 
increase of the field decrement. The position where the opposing molecular 
rotations balance (induction change neutral point) is therefore thrust from 
the cyclic extreme the greater the vibrational intensity. If the intensity of 
the vibrations be further increased, the molecular balancing would be again 
upset by bringing into play yet more stable groups tending to rotate 
positively, and the induction change would for the third time oppose the 
field change. 
Ultimately, however, this alternating process must cease when, under 
the influence of a sufficiently large decrement of field (or even increment of 
negative field, which this argument does not exclude), the increasing number 
of molecular groups tending to rotate negatively could just be balanced, and 
no more, by all the available remaining molecules still tending positively. 
Thereafter, negative rotation of the molecules would predominate, and the 
direction of the induction change would, on the superposition of vibrations 
of all intensities, however great, coincide with the direction of the field 
change. This process would continue until, with a sufficiently large incre- 
ment of negative field, all the molecular groups would tend to place 
themselves more and more in alignment with the direction of the field as 
the negative cyclic extreme is approached. The induction change due 
to superposed vibrations would coincide with that of the immediately 
preceding field change, the condition of things from which this hypothesis 
started at the positive cyclic extreme. 
The above deductions from the molecular theory of magnetisation are 
obviously in harmony with the experimental results obtained for cyclic 
field symmetrical about the origin. The shift of the neutral points within 
definite limits, and the correspondence between the direction of the 
induction change and that of the immediately preceding field change 
throughout a wider and wider range of cyclic field the weaker the 
intensity of the superposed vibrations or oscillations, are rendered im- 
mediately intelligible. 
It will be readily perceived that these deductions are not confined to 
cyclic fields symmetrical about the origin. It need only be supposed that a 
preponderance of the molecules are rotating in the direction of the field 
change as the cyclic amplitudes (not even necessarily of opposite sign) are 
reached for the above deductions to become fully applicable. The area of 
a large normal hysteresis loop may, for instance, be mapped out by a series 
of loops unsym metrical about the origin between the cyclic limits of, say, the 
positive extreme and increasing values of the negative field, as shown in 
