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 per cent. 



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"! ~ „_„ ~ , . 



ofpotash / 7 



Water 13*386 11*90 13*17 



The formula to which the computed quantities refer, is 



Thulite. 



3CaSi + 5AlSi + 12 H. 



Silica 42*808 



Alumina 31*144 



Lime 18*726 



Soda with a trace ofpotash 1*891 



Protoxide of iron 2*288 



Protoxide of manganese ... 1*635 



Water 0*640 99*132 



