52 Hillebrand — Analyses of Tysonite, Bastnasite, 



were found. The other earths were wholly precipitable by 

 potassium sulphate with exception of traces of what may be 

 oxides of the yttrium group. Approximate molecular weight 

 determinations of the combined oxides of these two groups 

 were made, and they show an appreciable difference, which 

 may, however, be due to the uncertainty of the method. It 

 may be mentioned that on ignition of the sulphates of these 

 earths they acted like the old didymium in that they lost 

 exactly two-thirds of their SO, on ignition over the full flame 

 of the Bunsen burner, a fact which would seem to exclude the 

 presence of lanthanum. Their solutions were pink and gave 

 pronounced absorption spectra. The ignited oxides freed from, 

 cerium were a dull dirty brown, which became nearly white 

 on blasting and acquired a distinct bluish cast on ignition in 

 hydrogen. No appreciable reduction in weight followed heat- 

 ing in hydrogen. The material saved is at the disposal of any 

 one desiring to examine these earths spectroscopically. 



Owing to the great difficulty in effecting complete decompo- 

 sition of the minerals by sulphuric acid at a single treatment, 

 the fluorine was obtained in condition for estimation by fusing 

 with potassium carbonate after mixing with silica in the pro- 

 portion of 0*6 gram mineral to 1 gram silica. 



Fragments of tysonite when held in the blast gave a distinct 

 crimson flame showing the lithium red line, but an alkali 

 determination failed to reveal more than a trace of this element. 



Of the bastnasite very little pure material could be sepa- 

 rated, and it was therefore impossible to place with certainty all 

 the loss shown by the analysis, but a portion of it is to be charged 

 to the oxides of the lanthanum group because of an accident. 



Sp. grav. of the bastnasite 5*12 at 27° C. and of the tysonite 

 6*10 at 28° C, which becomes 6-14 when corrected for 2*65 

 per cent of bastnasite. 



Analysis of Tysonite. Analysis of Bastnasite. 



Ce 2 3 42-89* Ce 2 3 37*71* 



La group 39*31f Lagroup.- 36'29f (low) 



F __ 28-711 F 7-83 



C0 2 -53 C0 2 ... 20-03J; 



CaO -18 Fe 2 3 -22 



Fe 2 3 -11 Na 2 0§ -18 



Na 2 0§ _ -30(approx.) H 2 -08 



112-03 102*34 



Less O for F, 12-08 Less O for F ... - 3-30 



99*95 99-04 



* 13 per cent Th0 2 ? * Mean of 37-73 and 37-69; in- 



\ At. w. 139-7 ; includes eludes -10 per cent Th0 2 ? 



-21 per cent soluble in K 2 S0 4 . f At. w. 141 ; includes -09 per 



± Mean of 28-86 and 28-56. cent soluble in K 2 S0 4 . 



§ With traces of K and Li. % Mean of 1 9*94 and 20-11. 



8 With traces of K and Li. 



