458 



PROCEEDINGS OP THE AMERICAN ACADEMY 



water found in the mineral dried for three months over sulphuric acid, 

 and (3 b) the percentages found in the same specimen subsequently 

 dried at 100° C. 



V. 



10.47 10.71 10.66 10.45 10.42 



The mean of (1), (2), (3 b), and (4) of Table VI. is 10.51. 



It would appear from analy.sis (3) that the amounts of water lost at 

 100° C. and over sulphuric acid, during a period of three months, are 

 very nearly identical. Assuming that 10.51 (the mean of the four 

 determinations above) represents the percentage of water in the min- 

 eral, dried at 100°, the following scheme contains the published an- 

 alyses of JefFerisite reduced to this basis. Analyses (1), (2), and (3) 

 are those of Prof. Brush, Dr. Koenig, and Mr. Thomas M. Clwtard 

 respectively : — 



(1.) 



Ratio ^ 



2.56 



2.49 



1.17 



(2.) 37.25 19.87 8.17 2.36 21.51 

 2.48 1.16 .31 .06 1.07 



Ratio ' 



2.48 



y 



1.47 



1.13 



J 



2.60 



10.51 

 1.17 



1.17 



99.67 



