LANTHANUM. 235 



For the quantity of La 2 (804)3 proportional to 100 parts 

 of BaSO^, we have five experiments, which may be given 

 equal weight and averaged together : 



Marignac 81.022 



80.934 



" Rammelsberg 79.276 



Czudnowicz 79.117 



Erie 79-921 



Mean, 80.054, ±z .270 



In all, there are seven ratios from whrch to calculate : 



(i.) Percentage of La^Oj in La2(SO^)3, 57.620, rb .0059 



(2.) BaClj : La2(S04)3 : : loo : 91.322, ± .048 — Marignac. 



(3.) BaSO^ : La.^(S04)3 : : 100 : 80.054, zb .270 



(4.) BaSO^ : LajOj : : 100 : 46.671, zb .075 — Holzmann. 



(5.) Percentage of LajOg in iodate, 23.447, zb .0216 — Holzmann. 



(6.) " " magnesian nitrate, 21.3056, zb .058 — Holzmann. 



(7.) " " carbonate, 68.47 — Hermann. 



These ratios give five values for the molecular weight of 

 lanthanum oxide, and. two for that of the sulphate: 



From (2) La2(SOj3 = 56S.488, zb .320 



" (3) " = 558.624, zb 1.888 



General mean, " = 568.212, zb .316 



Hence La = 140.346, d= .160. 



From (i) Laj03 = 325-791. ± -074 



= 325-674. lb .522 

 ==322.419, zb .113 



= 324-355. ± -923 



= 325.896, zb .488 



(4) 



(5) 



(6) 



(7) 



General mean 



=^ 324.810, zb .061 



Here the value derived from ratio (7) is given the weight 

 of a single experiment in ratio (1.) Hence La = 138.460, 

 =t .031. 



Combining the two values for La, we get this final result : 



From La203 La = 13S.460, zb .031 



" La2(SOj3 " = 140.346, zb -160 



General mean " z=r 138.526, zb -030 



Or, if = 16, La = 138.844. 



