526 SMITHSOXIAX MISCELLANEOUS COLLECTIONS VOL. 54 



Brill's ' analyses of samariiim sulphate, with the aid of the micro- 

 balance, need not be considered, for his two experiments, as recorded, 

 are widely discordant. The most thorough investigation is that by 

 Urbain and Lacombe,^ whose material was scrupulously freed from other 

 rare earths, an impurity to be discussed more fully a little later. The 

 samarium preparations of Urbain and Lacombe were derived from 

 different sources, gadolinite, monazite sand, etc., and the octohydrated 

 sulphate was analyzed by dehydration and calcination in the ordinary way. 

 In the next table I give their weights, and also three percentage columns, 

 as follows: A, percentage of Sag (804)3, in Sa2(S04)3.8H20. B, Sa^Og 

 in the hydrous sulphate. C, SaoOg in the anhydrous sulphate. The 

 different samples of material arc indicated by brackets: 



Mean, 80.338. 47.590. 59.238, 



±: .0048 ± .0026 ± .0040 



From A, Sa = 150.34. 

 From B, Sa = 150.49. 

 From C, Sa = 150.54. 



Two of the ratios given by Urbain and Lacombe's experiments may 

 now be combined with former series of determinations. First, for the 

 percentage of SaoOj in the anhydrous sulphate, giving the single deter- 

 minations of Marignac, Brauner and Kappel the weight of one experi- 

 ment in T'rbain and Lacombe's series: 



Marignac 59.166, ± .0199 



Cleve 59.1805, ± .0025 



Bettendorff 59.227, ± .0038 



Brauner 59.257, ± .0199 



Kappel 59.376, ±.0199 



Urbain and Lacombe 59.238, ±.0040 



General mean 59.2074, ± .0018 



1 Zeitsch. HiKiru. Olioiii.. 47, 464. VIC'}. 

 ^Tompt. IJcikI., 1.?S, 11G6. l!Xl4. 



