William E. Ford, 

 Molecular Volumes Specific Gravities 



legitimate, however, to eliminate certain analyses from considera- 

 tion. The specific gravities of Anal. 18, 27 and 31 for instance, 

 when compared with those of other similar analyses are obviously 

 too low. These are the most striking cases and there are others 

 which might well be considered also. Omitting, however, only 

 these three, the average difference between the measured and 

 calculated values becomes .034 or if the signs are used, — .005. 

 There seems no doubt, therefore, but that the figures chosen to 

 represent the specific gravities of the different molecules are 

 correctly chosen and that it is quite possible to calculate the 

 specific gravities of these minerals directly from their percentage 

 composition. 



