54 G. H. Williams — Piedmontite and Scheelite from the 



Si0 2 47-37 



A1 2 3 _. 18-55 



j Ce 2 3 0-75 



( R 2 3 (other rare earths) 1'28 



Fe 2 3 4-02 



Mn 2 3 6-85 



MnO 1-92 



CaO ._ _ ., 15-82 



MgO _ 0-25 



K 2 0-08 



Na 2 0-23 



H 2 G 2-08 



CuO 0-11 



PbO 0-14 



Total 100-05 



The silica is here 10 per cent too high for epidote, but as 

 the microscope showed that the only impurity was pure quartz, 

 it seemed quite justifiable to recalculate the analysis after de- 

 ducting 10 per cent of this substance. To substantiate this 

 conclusion another separation was attempted with greater care. 

 The piedmontite was very finely pulverized and only that por- 

 tion used which fell in a solution of methelyne iodide having 

 a specific gravity of 3*32. The microscope showed that there 

 was still a small quantity quartz admixed, although much less 

 than in the preceding instance. A determination of the silica 

 of this powder by Mr. Hillebrand gave 40*08 per cent. It 

 seems therefore certain that the recalculation of the analysis 

 given above on a basis of 3?-37 per cent silica would give very 

 nearly the composition of our piedmontite. The result thus 

 secured is as follows : 



SiO 



37-37 



Al O _. . 



22-07 



Ce (X__ 



0'89 



K 2 O s (other rare earths) 



FeO 



1-52 



4-78 



23 



Mn 2 3 



8-15 



MnO ._ 



2-285 



CaO 



18-825 



Mo-0 .... 



0-30 



KO 



0-81 



2 



Na O 



0-27 



HO ....... 



2-48 



AA 2 ^ " 



CuO 



0-13 



PbO 



0-17 







Total 



100-05 



