NEW YORK STATE MUSEUM 893 



Calcium carbonate 60^ to 86^ 



Magnesium carbonate less than 5^ 



Silica and alumina less than 10^ Group 4 



lOfo to 20fo Group 5 



more than 20 fo . Group 6 



Magnesium carbonate 6fo to 20 fo 



Silica and alumina less than 10^ Group 7 



lOfc to 20fo . . Group 8 



more than 20^ Group 9 



Magnesium carbonate more than 20 fo 



Silica and alumina less than lOfo Group 10 



lOfo to 20fo Group 11 



Calcium carbonate less than 60 fo 



Magnesium carbonate less than 6fo 



Silica and alumina less than 10^ Group 12 



10^ to 20^ Group 13 



more than 20^ Group 14 



Magnesium carbonate 10^ to 20^ 



Silica and alumina less than 10^ Group 15 



lOfo to 20fo Group 16 



more than 20fo Group lY 



Magnesium carbonate more than 20^ 



Silica and alumina less than 10^ Group 18 



10^ to 20;^ Group 19 



more than 20^ . Group 20 



If, now, limestone of a particular composition be sought, its 

 place in the tables can be readily ascertained. The first step is 

 to find from the " Key to grouping " above, in what group lime- 

 stones of the desired composition will fall. This ascertained, the 

 preliminary scheme immediately following this appendix will 

 show in what states limestones of that group may be found, the 

 limestones being designated by numbers corresponding to those 

 used in the regular '' Tables of limestone analyses '' which follow 

 the preliminary scheme. 



