1880.] On the Rare Earths and their Sulphates. 



47 



cally pure substances were employed both for the thermic, volumetric, 

 and magnetic experiments. The results only and not the details of 

 these experiments are given in the tables. 



Oxides. 



Compounds. 



Formula. 



Mole- 

 cular 

 weight. 



Specific 

 weight. 



Specific 

 heat. 



Mole- 

 cular 

 heat. 



Mole- 

 cular 

 volume. 



Beryllium oxide . . 



Be 2 3 ..,, 



753 



3-016 



0-2471 



1861 







24-97 



Aluminium oxide. . 





102*8 



3-990 



0-1827 



18-78 



25-76 



Sapphire cryst 



A1 2 3 



102-8 



3-990 



0-1879 



19-32 



2576 



Chrysoberyl cryst.. 



Alll 



BeJ *" 



959 



3-734 



0-2004 



19-22 



25*69 



Scandium oxide* . . 



Sc 2 3 .... 



1360 



3-864 



01530 



20-81 



3519 



Gallium oxidef . . . 



Grao0 3 . . . 



184-0 





0-1060 



19-50 





Yttrium oxide .... 



Y 2 3 .... 



227-0 



5-046 



0-1026 



23-29 



44-99 





In 2 3 .... 



274-8 



7-179 



0-0807 



2217 



38-28 



Erbium oxide£. . . . 



Er 2 3 .. . 



380-0 



8-640 



0-0650 



24-70 



43-98 



Ytterbium oxide . . 



Yb 2 3 .. . 



394-0 



9-175 



00646 



2545 



42-94 



Lanthanum oxide . 



La 2 3 . . . . 



3260 



6-480 



0-0749 



2442 



5031 



Didymium oxide . . 



Di 2 3 .... 



341-0 



6950 



0-0810 



2762 



4907 



Zirconium oxide. . . 



ZrOo 



1220 



5-850 



01076 



1313 



20-86 



Cerium bioxide . . . 



Ce0 2 .... 



1715 



6-739 



0-0877 



15-04 



25-45 



Thorium oxide. „ . . 



Th0 2 .... 



264-0 



9-861 



0-0548 



14-47 



26-77 



Hitherto it was supposed to be a general rule, that the atomic heat 

 of oxygen in any oxide was not less than 3"5 or greater than 5'1. The 

 numbers above given compel us, however, to assign a still lower value 

 to the atomic heat of oxygen in alumina and beryllia, viz., 2"34.§ Into 

 these oxides it enters with a minimum capacity of heat and volume. 

 From these earths upwards the molecular heat and volume of the ses- 

 quioxides gradually increase with increasing molecular weights. 



The following table shows that the molecular heat (1) of Er 2 3 , 

 Yb 2 3 , La 2 3 , and Di 2 3 nearly agrees with those for other sesqui- 

 oxides, determined by Regnault ; (2) that of Be 2 3 , approaches to 

 the same for alumina; and (3) that of Zr0 2 , Ce0 2 , and Th0 2 is as 

 high as the values for Sn0 2 , Ti0 2 , and zircon, determined by the 

 same author, and for Mn0 2 according to Kopp. The validity of 

 Neumann's law receives hereby a new confirmation. 



* According to Nilson. 



f For the oxide employed we are under obligation to M. Lecoq de Boisbaudran, 

 who placed 0138 grm. gallium at our disposal. 



X Professor Cleve has kindly placed at our disposal the purest erbia he has been 

 able to obtain. 



§ See the preceding paper, page 41. 



