348 



THE ATOMIC WEIGHTS. 



Frojn the last column, which indicates the percentage of Lafi.^ in 

 La,(S0,)3, we get, if SO3 = 80, La = 139.15. 



In his second paper,* published nine years later, Cleve gives results 

 similarly obtained, but with lanthanum oxide much more completely 

 freed from otlier earths. The data are as follows, lettered to correspond 

 to different fractions of the material studied : 



B- -8390 gim. La.^Og gave 1.4600 sulphate. 57.466 per cent. 



r 



I 



I 



■{ 



I. 1861 



•S993 



.8685 



-S5'5 



.6486 



.7329 

 1.2477 



1.1621 " 



1-5749 

 1.3367 

 1-4455 



Mean, 57.480, 4= .0040 



Hence with SO3 = 80, La = 138.22. 



From Brauner we also have two sets of determinations, both based upon 

 the conversion of pure La203 into La./S0j3. 



In his first paper, Brauner f gives only two syntheses, as follows : 



1-75933 g'-'ii. La,03 gave 3.05707 La2(.S0J 

 .92417 " 1.60589 " 



57.566 per cent. 

 57-549 



Mean, 57.5575 



This mean we may regard as of equal weight with Marignac's, and 

 assign to it the same probable error. 



In Brauner's second paper X six experiments are given ; but the weights 

 are affected by a misprint in the second determination, which I am un- 

 able to correct. Only five of the syntheses, therefore, are given below. 



.7S50 grm. La.Oj gave 1. 3658 La.,(S0,)3. 



2.1052 " 3-6633 



I. 0010 " I-74II " 



1.3807 " 2.4021 " 



1.5275 " 2.6588 



57.476 per cent. 

 57.467 " 

 57.525 " 

 57-479 " 

 57-451 " 



Mean, 57.480, ± .0084 



Brauner's weighings are all reduced to a vacuum. 



Both Bauer and Bettendorff made their determinations of the atomic 



* K. Svensk. Vet. Akad. Handlingar, No. 2, 1883. 



t Joiirn. Chem. Soc, Feb., 1882, p. 68. 



I Sitzungsb. Wien. .\kad., June, :8S2. Bd. 86, II Abth. 



