302 ELEMENTARY LESSONS ON [CHAP. v. 



Liquids were placed in glass vessels and suspended 

 between the poles of the electromagnet. Almost all 

 liquids are diamagnetic, except solutions of salts of the 

 magnetic metals, some of which are feebly magnetic ; 

 but blood is diamagnetic though it contains iron. To 

 examine gases bubbles were blown with them, and watched 

 as to whether they were drawn into or pushed out of the 

 field. Oxygen was the only gas found to be magnetic, 



34O. Quantitative Results. The magnetic or dia- 

 magnetic power of a substance may be expressed in 

 terms of a certain coefficient of magnetisation k (Art. 313), 

 which is the ratio of the intensity of magnetisation to the 

 magnetising-force of the field in which the substance is 

 placed. If the intensity of magnetisation be represented 

 by the symbol z, and the strength of the magnetising 

 field by H, then 



* = -H. 



For paramagnetic substances k has + values ; for diamag- 

 netic substances k has values. According to Thalen 

 the value of k for iron is + 45 ; but Barlow's highest 

 value for iron was only 32-8. For bismuth the value of 

 k is -0-000002 5 according to Maxwell. The repulsion 

 of bismuth is immensely feebler than the attraction of 

 iron. Pliicker compared the magnetic powers of equal 

 weights of substances, and reckoning that of iron as one 

 million, he found the following values for the "specific 

 magnetism " of bodies : 



341. Apparent Diamagnetism due to sur- 

 rounding Medium. It is found that feebly magnetic 

 bodies behave as if they were diamagnetic when 



