Appendix: D 



KEY TO THE TABLES OF LIMESTOIS^E AITALYSES 



BY EDWIN C. ECKEL C. E. 



The limestone analyses which follow this section were collected 

 by Dr Heinrich Ries. They have been carefully rearranged and 

 revised in this office. Each analysis has been compared with its 

 original published record, and the tables are, it is believed^ en- 

 tirely reliable. 



At the suggestion of Dr E. J. H. Merrill the present writer has 

 prepared a key to the tables of analyses to facilitate reference. 

 This key is based on composition, and will be of use in determining 

 the areas from which limestones of any given composition may 

 be obtained. A table has been prepared in which its results are 

 summed up, classified both by composition and by states. 



Eor most commercial uses the components of greatest interest 

 in a limestone are its lime carbonate, magnesium carbonate, and 

 silica plus alumina. The limestones whose analyses are given in 

 the following tables have, therefore, been first divided into four 

 primary groups, the grouping being based on the percentages of 

 lime carbonate in the rock. Each of these primary groups is then 

 subdivided, according to the percentages of magnesium carbonate 

 present. Finally, the secondary groups thus obtained are again 

 divided according to the percentages of silica and alumina con- 

 tained in the rocks. As shown in the summary below, 20 groups 

 are thus formed. 



KEY TO GROUPING 



Calcium carbonate 95^ or over Group 1 



Calcium carbonate 85^ to 95^ 



Magnesiu-m carbonate less than 5^ Group 2 



Magnesium carbonate over 6fo Group 3 



