Petalite, Spodumene, Poonalite, Thulite. 103 



contains 2'19 per cent, of carbonate of oxide of lead, accord- 

 ing to the analysis of Professor Kersten, and 3*859 per cent, 

 according to the analysis of M. Bottger. Hence the pro- 

 portion of carbonate of oxide of lead appears to be variable, 

 like the proportion of carbonate of strontian in common 

 arragonite, which, according to Stromeyer, varies from 0'5 to 

 4'01 percent. 



ANALYSES OF PETALITE AND SPODUMENE. 



[From Poggendorff's Annalen, B. xlix.] 



Petalite analysed by M. Robert Hagen in the laboratory 

 of Prof. Heinrich Rose, gave the following results : 



(1.) Oxygen. (2.) Oxygen. 



Silica 77-812 40-423 77'067 40-036 



Alumina... 17'194 8-030 18-000 8-406 



Lithia 2-692 1-484 2-660 1-466 



So da 2-302 0-588 2-273 0-581 



Spodumene gave 



Oxygen. 



Silica 66-136 34-357 



Alumina 27'024 12-621 



Protoxide of iron 0-321 0-098 



Lithia 3-836 2*126 



Soda 2-683 0-686 



RESULTS OF ANALYSES OF POONALITE AND THULITE. BY 

 PROF. C. G. GMELIN. 



[From Poggendorff's Annalen, B. xlix.] 

 Poonalite. 



Observed. Oxygen. Computed. 



Silica 45-120 23'44 45-07 



Alumina 30-446 14-22 31*33 



Lime 10-197 2-86 10-43 



Soda with a trace\ ^ 



of potash / 657 



Water 13-386 11-90 13-17 



The formula to which the computed quantities refer, is 



3CaSi + 5 Al Si + 12 H. 

 Thulite. 



Silica 42-808 



Alumina 31-144 



Lime 18*726 



Soda with a trace of potash 1-891 



Protoxide of iron 2-288 



Protoxide of manganese ... 1*635 



Water., , 0-640 99*132 



