690 Mr. S. C. Laws on the Change of Resistance of Metals 



With the apparatus described above, readings of the change 

 of resistance were also made at the temperatures 16° C. and 

 97°*7, that is, with the jacket empty and filled with steam. 



The results obtained are tabulated below : — 



December 11th, 1908. 

 £ = 16° C. Y = 180. X=1410. r = 16-0. 



c. 



H. 



Deflexion on 

 reversal. 



fo-XJO* 



— xio 4 . 



H2X10 -7 . 









r 





1-8 



8450 



221 



30-5 



1-91 



7-14 



2-5 



9300 



27-8 



38-3 



2-39 



8-65 



3-4 



10200 



32-4 



447 



2-79 



10-4 



4-4 



11000 



37-8 



521 



326 



121 



56 



11800 



42-1 



58-1 



363 



139 



75 



12600 



481 



66-3 



414 



159 



10-0 



13300 



51-8 



71'4 



4-4(> 



177 



December 10th, 1908. 

 * = 97°-7. Y=240. X-1730. r=*=21*l. 



c. 



H. 



Deflexion on 

 reversal. 



3rxl0 4 . 



^xio*. 



r 



H 2 xl0 7 . 



1-8 



8450 



8-3 



15-4 



073 



7-14 



2'5 



9300 



10 



185 



0-88 



8-65 



3-4 



10200 



11-6 



21-4 



1-Oi 



104 



4-4 



11000 



13-3 



245 



1-16 



12-1 



5-6 



11800 



159 



29-3 



1-39 



13-9 



7-5 



12600 



183 



33-8 



1-60 



159 



10-0 



13300 



19-7 



36-4 



1-73 



177 



It will be noticed that the value of the magnetic field 

 produced by a given current .in the magnet coils is not 

 affected by the changes of temperature of the bath. 



This fact was ascertained by a special apparatus erected to 

 test the point. This apparatus consisted of a few turns of 

 fine insulated copper wire wound on a very small ebonite 

 disk with the ends of the wire connected to a small split tube 

 commutator. The disk and commutator were attached to a 

 light brass spindle so that the former revolved within the 

 steam-jacket and in a line with the pole-pieces of the 

 magnet. — occupying in fact the same position as the wire 

 under examination in the above experiments. 



