492 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



For the percentage of yttria in the sulphate we now have the following 

 data, to be combined in the usual way. The one determination by 

 Muthmann and Bohm is arbitrarily given equal weight with the figure 

 assigned to Brill : 



Popp 51.208, ± .0110 



Uelafontaine, first 49.998, ± .0810 



Delafontaine, second 48.230, ± .0550 



Bahr and Bunsen 49.2G95, ± .0233 



Cleve and Hoeglund 48.605, ± .0096 



Cleve, later 48.503, ± .0029 



Jones, syntheses 48.467, ± .0025 



Jones, analyses 48.472, ± .0024 



Muthmann and Bohm 48.482, ±.0100 



Bodman 49.040, ± .0102 



Brill 48.632, ± .0100 



General mean 48.543, ± .0014 



If we reject the first four of the values in this combination, the mean 

 becomes 48.495, ±.0014. Hence Yt = 89.040, ±.0047, as compared with 

 Yt = 89.299, derived from the mean of all. The determinations, previous 

 to those of Cleve and Hoeglund, are of no present value. 



The determinations made by Feit and Przibylla,^ by their volumetric 

 method, are as follows : 



Mean, 89.346, ± .0135 



From the sulphate, when S = 32.06G7,±. 00075, Yt = 89.040, ±.0047. 

 Combined with Feit and Prziln'lla's value the general mean becomes 



Yt = 89.094, ± .0044 



This is probably too high, by at least 0.1. But it would be unwise to 

 reject any of the values included in the final combination. 



' Zeitsch. anorg. Chem., 50, 262. 1906. For the proctss, see under lanthanum. 



