14 
i\rR. J. REGINALD ASHWORTH; 
grows less, and ultimately changes sign aiid becomes negative. The rise and fall 
suggest some connexion with susceptiliility, for which there is evidence in another 
group of experiments descril)ed later on. 
In the second place, wlien tlie magnetic intensity is rising, the final intensit}", after 
a series of heatings and coolings, is always less than Initially, and ^ is therefore 
negative, but on gradually removing successive fractions of the magnetism, then, at 
each stage, heatings and coolings jiroduce a f/ain of magnetism, and the loss or gain 
is always much greater the smaller the intensity ; indeed, the gain becomes very 
large at low intensities on the downward path, and at last, ^vhen the reversed 
magnetic field has been increased so far as to leave a small reversed residual maeiietic 
o 
intensity, then heatings and coolings clear this out and restore a small magnetisation 
of the original kind. 
Ihese results could l)e obtained repeatedly; thus, in the following example, which 
is a typical one, after magnetising to saturation a reversed force left a residual of 
109'2, which was augmented l)y lieating and cooling to 167’2 with a positive 
coefiicient of + 3'30 X 10“’'^, a further application of reversed force left a residual 
of 15'2 in the opposite direction, and then as follows :— 
Cold. 
Hot. 
- 15-2 
+ 19-0 
+ 11-4 
Direction of original magnetisation restored. 
f 19-0 
+ 23-0 
+ 22-2 
+ 24-9 
+ 24-3 
+ 26-2 
+ 24-7 
[The coefficient is negative and equal to 
+ 26-8 
j -0-00085. 
Here there is a change in the direction of the magnetisation due to heating and 
cooling and a coefiicient which is now negative. But the negative coefiicient is found 
to Ijecome less negative when the intensity thus restored is greater, as the following 
ta])le shows :— 
Final intensity after 
reversal. 
Coefficient. 
j 
+ 23-8 
-0-00120 
+ 26-8 
- 0 - 00085 
4" 30 * 4 
-0-00047 
+ 63-6 
- 0-00029 
and no doubt a zero coefiicient would be reached for a still higher intensity than 63'6. 
