318 Mr. Take Sone'ow the Magnetic Susceptibility 



was carefully observed at each set of observations with a 

 thermometer suspended near the measuring tube in the 

 space between the poles of the electromagnet. A current 

 of water was constantly passed around the electromagnet 

 during the observation. 



§ 5. Aie. 



The magnetic susceptibility of the atmospheric air has 

 been determined by many investigators, such as Faraday, 

 Becquerel, Quincke, and more recently by Curie. But other 

 investigators such as Du Bois, Hennig, and Piccard, have 

 deduced the susceptibility of air from that of oxygen by 

 neglecting the susceptibilities of nitrogen and other gases 

 present in the atmosphere. 



In the following table, the values of the volume suscepti- 

 bility of air and also the ratio of the susceptibilities of air 

 and oxygen in four cases, in which the susceptibilities were 

 independently determined, are given : — 



Table I. 



Date. Observer. K a . W\ t. K J K 0>- 



1853 Faraday* 0'024 ... 0-184 



1855 Becquerel t 0-025 ... 0"208 



1888 Quincke \ 0-032 16° 0*248 



1895 Curie § 0-027 20° 0'232 



1888 Du Bois || 0-024 15° 



1893 Hennig «[ 0-024 25° 



1913 Piccard-* 0"029 20° 



* M. Faradav, Exp. Res. of Elec. (3) p. 502. 



+ E. Becquerel, Ann. de Chim. et de Phys. (3) xliv. p. 223 (1855). 

 X Gt. Quincke, Wied. Ann. xxxiv. p. 401 (1888). 

 § P. Curie, Journ. de Phys. iv. p. 197 (1895). 

 H H. Du Bois, Wied. Ann. xxxv. p. 137 (1888). 

 5] R. Hennig-, Wied. Ann. 1. p. 485 (1893). 

 ** A. Piccard, Arch, de Geneve, xxxv. p. 458 (1913). 



Tn the above table we see that the magnetic suscepti- 

 bility of air as obtained by several observers shows a large 

 discrepancy, and also the ratio of the susceptibilities of air 

 and oxygen directly determined is not constant. Hence 

 it is to be concluded that the susceptibility of air and its 

 relation to that of oxygen are not yet correctly known. 



In the present research the susceptibility of the atmo- 

 spheric air was determined relatively to that of redistilled 

 water. The air to be examined was introduced into the 

 compressing cylinder after passing through the tubes con- 

 taining solid potassium hydroxide, calcium chloride, phos- 



