MEMOIRS AMERICAN ACADEMY. VOL. XIII. 
PLATE VIM. 
1800 
1 700 
1600 
1500 
1400 
1300 
1200 
1100 
1000 
I 
I 
! 
I 
THROUGH 
FLUORITE 
I 
I 
I 
AIR. 
I. 
HYDROGEN 
AND AIR. 
I. HYDROGEN. 
ABSORBTION OF FLUORITE. 
