LANTHANUM. 



349 



weight of lanthanum by the same general method as the preceding 

 Bauer's data * are as follows : 



.6431 grm. La.^Og gave I.1171 sulphate. 57.569 per cent. 



.7825 " 1. 3613 " 57.482 " 



1.0112 " I. 7571 " 57-549 " 



.7325 " 1.2725 " 57.564 " 



Mean, 57.541, ± .0136 



Bettendorff found f- 



.9146 grm. LajOg gave 1.5900 sulphate. 57-522 per cent. 



•9395 " 1-6332 " 57-525 " 



-9133 " 1-5877 " 57-523 " 



I. 0651 " I. 8515 " 57-526 " 



Mean, 57.524, zb .0006 



We may now combine the similar means into general means, and de- 

 duce a value for the atomic weight of lanthanum. For the percentage of 

 oxide in sulpbate we have estimates as follows. The single experiments 

 of Czudnowicz and of Erk are assigned the probable error and weight of 

 a single experiment in Hermann's series : 



Czudnowicz 58 



Erk 57 



Hermann 57 



Zschiesche 57 



Marignac 57 



Cleve, earlier series 57 



Cleve, later series 57 



Brauner, earlier series 57 



Brauner, later series 57 



Bauer 57 



Bettendorff. 57 



General mean 57 



668. 



068, 

 654, 

 021, 



d= .027 

 ± .027 

 ifc .016 

 ± .051 



5475. ± -0115 



619, zfc .C085 

 480, ± .0040 

 5575, ±.0115 



480, zh .0084 

 541, ± .0136 

 524, zb .0006 



522, 



.00059 



This result is practically identical with that of Bettendorff, Avhose work 

 seems to receive excessive weight. The figure, however, cannot be far 

 out of the way. 



For the quantity of La./SOJa proportional to 100 parts of BaSO^, we 

 have five experiments, which may be given equal weight and averaged 

 together : 



Marignac 81.022 



Marignac So. 934 



Rammehberg 79.276 



Czudnowicz 79. 1 1 7 



Erk 79.921 



Mean, So. 054, ± .270 



* Freiburg Inaugural Dissertation, iS 

 ■f Ann. d. Chem., 256, 168. 



