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



The 1*018 grm. of oxide of lanthanum contained accordingly 

 0*0476 of oxide of didymium. 



The oxide obtained by the solution of the metal in nitric 

 acid consisted therefore, in 100 parts, of 



Oxide of lanthanum . . =93*23 



Oxide of didymium . . =4*52 



Oxide of iron = 1*49 



Silica = 0*51 



Alumina = 0*25 



100-00 



Since it follows, from the oxidation experiment above de- 

 tailed, that 100 parts of oxide correspond to 84*737 parts of im- 

 pure metallic lanthanum, which, after subtraction of the metallic 

 impurities calculated from the analysis, contain 79*431 of 

 pure lanthanum, corresponding to 93*229 pure oxide of lan- 

 thanum, we have for the percentage composition of the pure 

 oxide as directly found : — 



Lanthanum .... 85*20 



Oxygen 14*80 



100*00 

 This composition is almost identical with that deduced from 

 Cleve's* analysis of the lanthanum sulphate (made with great 

 care for the special purpose of determining the atomic weight 

 of lanthanum), on the assumption that the quantity of oxygen 

 in the oxide is one third of that contained in the sulphuric acid 

 necessary for saturation: — 



Lanthanum .... 85*29 

 Oxygen 14*71 



100*00 



The sample employed for the determination of the specific 

 heat was found by analysis to have the following composition: — 



Lanthanum .... 93*74 



Didymium 



. . 4*59 



Iron .... 



. . 1*23 



Silicon . . . 



. . 0*28 



Aluminium . . 



. . 0*16 



100*00 



By means of formula (3) the specific heat of pure lanthanum 

 is found to be 



0*04485. 

 Assuming, with Cleve, that the weight of the atom of lan- 

 * Abhandhmg. d. Schwedischen Akad. vol. ii. No. 6. 



