350 THE ATOMIC WEIGHTS. 



In all, there are six ratios from wliich to calculate : 



(r.) Percentage of La.^Og in La2(SO^)3, 57.522, ± .00059 



(2.) 3BaCl2 : La2(.S04)3 : : 100 : 91.322, ± .048 — Marignac 



(3.) 3HaSO^ : La2(Soj3 : : 100 : 80.054, ± .270 



(4.) 3BaSO^ : La^Og : : lOO : 46.671, ± .075 — Holzmann 



(5.) Percentage of La^Og in iodate, 23.447, ± .0216 — Holzmann 



(6.) Percentage of La.^O., in magnesian nitrate, 21.3056, ± .05S — Holzmann 



Hermann s single experiment on the carbonate is omitted from this 

 scheme as being unimportant. 



For the reduction of these data we have — 



= 15.879, ± .0003 N = 13.935, ± .0021 

 CI =- 35.179, zh .0048 C ^ 11.920, =h .0004 



1 =r 125.888, 4= .0069 ' Mg= 24. 100, =h .001 1 



S ^ 31.S28, =b .0015 Ba ^ 136.392, ± .0086 



For lanthanum suli)hate two values are obtainable : 



From (2) La.,{SO^).^ = 566.425, ± .2999 



From (3) " =556.542, ± 1.8729 



General mean. .. .' L:i2(S04)3 = 566. 182, ± .2961 



Hence La = 140.075, d= .1481. 



For the oxide there are four independent values, as follows : 



From (i) La.^Og = 322.825, =h .0090 



From (4) " ^322.460,^.5215 



From (5) " =320.726, ±.3159 



From (6) " :;= 322.904, zb .9107 



A glance at these figures shows that the first alone deserves considera- 

 tion, and that a combination of all would vary inappreciably from it. 

 Taking, then, La,03 = 322.825, rb .0090, we get- 

 La = 137-594, ± .0046; 



or, with = 16, La == 138.642. 



^If we take tbe concordant results of Cleve's and Brauner's later series, 

 which give the percentage of La.,03 in La./SOJj as 57.480, then La = 

 137.316. Possibly this value ma}^ be better than the other, but the evi- 

 dence is not conclusive. 



