M. Gmeliu's Chemical examination of J^ourmaline. 275 



apatite. Specific gravity = 3.246, at + 8° R. 2. Black tour- 

 maline, from Eibenstock, in Saxony. Specific gravity — 3.123, 

 at -f 8° R. 3. Black tourmaline, from Chesterfield, in North 

 America. Specific gravity = 3.102, at + 8° R. 



C. Tourmaline zvldch contains a considerable quantity of 

 Magnesia. 



1. Black tourmaline, from Karingbricka, in the Swedish pro- 

 vince of Westmanland. Specific gravity =z 3.044, at -f- 9| R. 

 2. Black tourmaline, from Raben^tein, in Bavaria. Specific gra- 

 vity r= 3.113 at -f 13 R. 3. Black tourmaline from Greenland. 

 Specific gravity = 3.062, at -J- 5 J R. 4. Dark brown tourma- 

 line, in mica-slate, from St Gotthardt. Specific gravity not ac- 

 curately determined. 



The great loss in the analysis of the St Gotthardt tourmaline 

 is not easily explained : it may be owing to the escape of a 

 volatile alkali. 



* With trace of Magnesia. f With trace of Magnesia. 



§ With Potash and trace of Magnesia, 



With trace of Manganese. 



s2 



