594 CROSS, IDDINGS, PIRSSON, WASHINGTON 



„ . (Mg, Fe)0 7 5 J . . 



Section 2 : v % _ / < - > - , domiric. 

 CaO i 3 



. (Mg, Fe)0 5 3 , . , . 



Section t. : - — ° ^ „ — < - > - , calcimine. 

 CaO 3 5 



n . (Mg, Fe)0 3 i . , ' . 



Section 4 : v °' ' < - > - , docalcic. 

 CaO 5 7 



„ . (Mg, Fe)0 i 



Section 5 : - — ° ,/ — < - , percalcic. 



CaO 7 



Subrang. — Subrangs are made on a basis of the special char- 

 acter of the variable or compounded chemical quality used in 

 forming Ra?ig. In Classes I, II and III this variable quality is 

 in the ratio of alkalies, potash and soda, and the following sub- 

 divisions are recognized for Rangs I, II and III. 



In Rangs IV and V of Classes I, II and III only three 

 divisions are used because of the subordinate amount of alkalies. 

 These Subrangs are : 



K 2 C 5 

 Subrang 1 : ^ , > - , prepotassic. 



K 2 0' 5 3 



Subrang 2 : XT * ^ . < - > - , sodipotassic. 



Na 2 0' 35 



K 2 0' 3 

 Subrang 3 : Na * Q , < - , presodic. 



In Classes IV and V the variable quality is in the miric 

 content. The alkalies are so preponderantly sodic that they do 

 not require subdivision, and no distinction on a basis of the rela- 



