592 CROSS, IDDINGS, PIRSSON, WASHINGTON 



Suborder 2 : 

 Suborder 3 : 

 Suborder 4 : 

 Suborder 5 : 



Rang. — The division for Rang is based on the general chem- 

 ical character of the bases in the minerals of the preponderant 

 group in each Class, that is, in the salic or femic minerals used 

 for the formation of Orders. 



For salic minerals this is expressed by the terms alkalic and 

 calcic, which relate to the feldspars and lenads. Divisions 

 are based on the proportions of molecules of K 2 0' + 

 NagO', to CaO' in these minerals, K 3 0', Na 2 0' and CaO' 

 being the parts of these rock components allotted to salic min- 

 erals. The divisions in Classes I, II and III are fivefold: 



K 2 0'+Na 2 0' 

 Ran S l ■ CaO- 



K 2 0'+Na 2 0' 

 Ran S 2: CaO- 



K 2 0'+Na 2 0' 

 Ran ^ 3: CaO- ~ 



K 2 0'+Na 2 0' 

 Ran ^ 4: CaO- 



K 2 0'+Na 2 0' 

 Ran ^ 5: CaO- 



In Order 6, where feldspar is dominant over the lenads, 

 only the first four Rangs will occur, in Order 7 only the first 

 three, in Order 8 only the first two, and in Order 9 only the 

 first one. 



For femic minerals the general chemical characters of the bases 

 are commonly expressed by the terms ferromagfiesiati, calcic, and 

 alkalic. But three independent factors are not to be employed 



