608 PROCEEDINGS OP THE AMERICAN ACADEMY. 



the same origin are all of the same order, the percentages varying only 

 within the limit of error of the analytical methods employed. 



1. Weardale (England) fluorite. Purple in color. Not very 

 transparent. Contains many inclusions visible under the microscope. 

 Amount taken for analysis, 250 gms. Gas evolved, 320 c.c. Tem- 

 perature of heating, 280°. Time of heating, four hours. Water pro- 

 duced, 2.4 c.c. 85.3 c.c. taken for analysis. 



Composition : 



Carbon dioxide 46.7 % 



Oxygen . . . . 

 Carbon monoxide 

 Hydrogen . . . . 

 Nitrogen (remainder) 



2.9 " 

 16.7 " 

 18.6 " 

 15.2 " 



100.1 



2. Same sample. 250 gms. Gas evolved, 280 c.c. Temperature, low 

 red heat (about 650°). Time of heating, two hours. Water, 3 c.c. 



Composition : 



Carbon dioxide 42.9 % 



Oxygen 2.0 " 



Carbon monoxide 21.7 " 



Hydrogen 16.4 " 



Nitrogen (remainder) .... 16.4 " 



99.4 " 



3. Perfectly clear Weardale fluorite crystal. Contains only very 

 minute inclusions, and only a few of these. Deep purple color, slightly 

 brownish. 200 gms. Gas evolved, 68.5 c.c. Temperature, 340°. 

 Time of heating, five hours. Water, about 1 c.c. 



Composition : 



Carbon dioxide 65.3 % 



Oxygen 0.8 " 



Carbon monoxide 2.0 " 



Hydrogen 26.4 " 



Nitrogeu (remainder) .... 4.7 " 



99.2 " 



