independent of Changes of Temperature. 217 



Table IV. 



No. 



d. 



m. 



E. 



J i. 



b 



A 



a 



o-oo. 



ox d. 



0000. ■ 



33 



© fist stage 

 -3 « 2nd stage 

 $ 1 3rd stage 

 Q 



*216 

 0-195* 

 0-163* 

 -112* 



3 -535 

 2-875 

 1-995 

 935 



55 -3 

 61 -3 

 73-6 

 107-5 



530-3 

 478-0 

 474-5 

 485-5 



428 -5 

 464-6 

 468-9 

 482-9 



0*192 

 0-028 

 0-012 

 0-005 



— -0136 

 -0-0155 

 -0 -0196 

 -0-0292 



294 

 302 

 319 

 327 



intensity each time the wire is redissolved, remembering that after 

 the initial magnetisation the wire was not subjected to any further 

 magnetising process. Thus, for example, No. 33 has an intensity, 

 after being heated and cooled, of 428 ; upon dissolving off an outer 

 layer the intensity rises to 478, which in its turn is reduced by 

 heatings and coolings to 465 ; dissolving it a second time raises the 

 intensity to 475, and so on. The recovery of magnetic intensity 

 after dissolving in acid is most likely to be ascribed to diminution of 

 the self-demagnetising force resulting from increase of dimension 

 ratio. The intensities, however, after each dissolving, namely 478, 

 475,486, are sufficiently constant to indicate that the intensity is 

 nearly uniform throughout the wire, and this confirms an experi- 

 ment of Bouty's.f 



The next two wires have been grouped in a separate table from the 

 others, as they came from a different factory, being made in 

 Sheffield. They are thicker than the former wires, and the thicker 

 of the two, rTo. 34, has now a positive coefficient. By continually 

 reducing the diameter of this wire, the coefficient ultimately changes 

 sign and becomes negative. 



Table V. 



No. 



d. 



m. 



E, 





V 



0. 



a. 



o-oo. 





32 



0-227 



3-875 



52 -8 



490 



1 



340-6 



-305 



-0-0015 





34 



0-262 



5-145 



45 -8 



388 



•6 



271-9 



0-304 



+ 0-0220 





'1st stage . . . 



0-223J 



3-740 



53 -7 



307 



•2 



299 -2 



0-026 



+ 0-0193 





2nd stage . . 



-204X 



3-130 



58-7 



297 



•9 



290-3 



0-025 



+ 0-0184 



i 



3rd stage . . 



-152+ 



1-742 



78-8 



306 



•6 



300-2 



0-021 



+ 0-0082 



Q 



^4th stage . . 



0-075^ 



0-427 



159 -2 



292 



•5 



287-1 



0-019 



-o-oioo 



Length, 12 cm. 



* Calculated from the weight, 

 t 'Ann. Scient. de l'Ec. Norm.,' [2], 5, p. 131. 

 J Calculated from the weight. 

 VOL. LX1I. E 



