434 Thermoelectric Power and Magnetisation. [Apr. 11, 



and evidently cannot be made to resemble it by applying the correction 

 for mechanical compression. The compression curve (r) was constructed, 

 like that for nickel, from values of I furnished by Ewing; Young's 

 modulus was taken as 2 x 10 9 , the value found by Tomlinson* for 

 unannealed cobalt being 2005 x 10 6 . 



The thermoelectric curve (S) was given by a strip of rolled cobalt, 

 for which I am indebted to the kindness of Messrs. Henry Wiggin 

 and Co., of Birmingham. It is of interest as indicating the similar 

 behaviour of a very different sample of the metal. 



If there is any relation between the thermoelectric and the strain 

 phenomena in cobalt, it is obviously disguised by some cause which has 

 yet to be discovered. 



[Note added May 23, 1904. — Some further experiments have been 

 made with specimens of cobalt which had been very thoroughly 

 annealed. For cast cobalt the change-of-length curve is entirely 

 altered by annealing, becoming, at least in fields up to 1360 units, a 

 straight line represented by K = 0-056H, where R is the retraction in 

 ten-millionths. The thermoelectric curve is considerably lowered, but 

 in other respects is not much affected. No relation between the 

 thermoelectric and the strain phenomena could be traced. 



From an examination of the curves in fig. 10 it appears that the 

 thermoelectric power of the unmagnetised with respect to the 

 magnetised cast cobalt is proportional to the compressive stress, and 

 consequently to the square of the magnetic induction.] 



* * Koy. Soc. Proc.,' vol. 39, p. 530, 1885. 



