( 117 ) 



motions according- to the same formula and for the same reasons. 

 In the present paper we shall confme our attention to a short 

 résumé of the results which we have obtained up to the present 

 in which we shall also include those referring to diamagnetic 

 properties. In a further communication we hope to give the results 

 of the experiments upon which we are still engaged and at the 

 same time further details of the experimental method. To attain a 

 greater degree of certaint}^ we used with the apparatus described in 

 Comm. No. 116, a new cryomagnetic apparatus with which it is possible 

 to measure electromagneticallj' the forces exerted upon the experimental 

 substance by a strong magnet, and with which it is possible to place 

 at ivill the experimental substance at the point of maximum attraction 

 or repulsion as long as it occupies a space of small dimensions, or, 

 if the experimental substance be in the form of a cylinder, to place 

 it with its one extremity in the pole gap. 



§ 2. Numerical results. The values given below are the results 

 only of preliminary calculations. There are still some corrections 

 to be applied which have not yet been fully investigated, but these 

 in all probability will not, in the most unfavourable circumstance, 

 exceed 2 "/(,. The numbers given are, of course, mean values, / is 

 the specific susceptibility or the magnetisation coefficient per gram, 

 and T is the absolute temperature. 



TABLE I. 



1) Prof. G. Urbain to whom we are greatly indebted has kindly placed this 

 substance at our disposal as well as the Dysprosium oxide (table III) and some 

 others of the group of rare earths which have not yet been studied. 



