of Cerium, Lanthanum, and Didymium. 



117 



thanum is 139, corresponding to the formula La 2 3 , this 

 number gives the atomic heat as 6*23 ; if we adopt the for- 

 mula LaO, the atomic heat is 4*15, which does not agree with 

 the law of Dulong and Petit. 



The oxide of lanthanum must therefore likewise be regarded 

 as a sesquioxide. 



C. Specific Heat of Cerium. 



The smaller globules of cerium were employed in this as in 

 the former experiments, and for the same reason. 



The value of the constant Gci is obtained from the following 

 elements: — 



V =1-17, s g =2-5, 



G g =0-1601, ^ = 6-728, 



G m = 2-0935, t =40°, 



P =0-759. 

 It amounts to 



G— 0-00089. 



The experiments with the ice-calorimeter gave: — 





Weight of 



cerium, in 



grms. 



Weight of 

 glass enve- 

 lope. 



Weight of 



air in glass 



envelope. 



Initial tem- 

 perature. 



Duration of 

 the experi- 

 ment. 





Gm. 



a g . 



Qi. 



t 



MV-M . 



Exp. I. ... 

 Exp. II... . 



20935 

 2-0935 



0'16<»1 

 01601 



0-00089 

 0-00089 



99°-70 

 94°-93 



60' 

 60 r 





Scale- 

 variation 

 before 

 experiment. 



Scale- 

 variation 

 after 

 experiment. 



Retraction 

 of mercury in 

 scale- 

 divisions. 



Reduced 

 retraction. 





Z"o.. 

 m ' 





Qo-Qr 



T. 



Exp. I. ... 

 Exp. II.... 



0060 

 -0040 



0-067 

 -0-026 



184 



188-0 



187-81 

 186-42 



Hence we have for the specific heat of cerium : — 



From Exp. I. . . . 0*04613 

 From Exp. II. . . . Q-Q4554 



Mean . . . 0*04583 



