114 Dr. W. F. Hillebrand on the Specific Heats 



Assuming that didymium oxide has the formula DiO, we 

 obtain from analysis III. for the atomic weight of didymium 

 the value 96*52*, and for its atomic heat 4*40, which differs so 

 considerably from the atomic heat of the other elements as to 

 render the formula DiO completely invalid. If, on the other 

 hand, we adopt the formula Di 2 3 , the weight of the didymium 

 atom becomes one and a half times that of the above number, 

 namely 144*78, and its atomic heat becomes 6*60, a number 

 which agrees most satisfactorily with Dulong and Petit's law. 



The oxide of didymium is accordingly, without doubt, a 

 sesquioxide. 



B. Specific Heat of Lanthanum. 



The following data have served for the determination of Qr. — 



Exp. I. Exp. II. 



=0-60. 1-00 



= 0-1721 0-2154 



= 0-8911 1-6828 



= 2-5 2-5 



= 6-049 4-049 



=40° 40° 



= 0-756 0-758 



By substituting these elements in formula (2), we obtain 

 From Exp. I. . . G,=0'00043, 

 From Exp. II. . . G, = 0'00071. 

 The following are the elements for the determination of the 



specific heat: — 



Y 



. • • 



re 



• • 



s 

 g 



• 



t 



• • » 



P . 



, , 





"W eight of 



lanthanum, 



in grms. 



Weight af 

 glass enve- 

 lope, in 

 grms. 



Weight of 



air in glass 



envelope. 



Initial tem- 

 perature. 



Duration 

 of the ex- 

 periment. 





Gm. 



<v 



GJ. 



t. 



M x -M . 



Exp. I. ... 

 Exp. II.... 



08911 

 16828 



01721 

 0-2154 



000043 

 000071 



99°76 

 99°-69 



49'. 

 50'. 





Scale- 

 variation 

 before 

 experiment. 



Scale- 

 variation 

 after 

 experiment. 



Retraction 

 of mercury in 

 scale- 

 divisions. 



Reduced 

 retraction. 





1°. 

 m m 



Ml 



Qo-Qr 



T. 



Exp. I. ... 

 Exp. II.... 



0105 



0-058 



011 



0-08 



104-5 

 174 6 



10977 

 17805 



= 16. 



