— 9 - 



ate from the old sea as the result of evaporation. But I 

 am rather of the opinion of Anikin that the salts are mainly 

 due to the constantly continued chemical weathering. 



Chlorides and sulphates occur most frequently both in the 

 soil of the desert and in the salt-lakes. These two groups of 

 salts are often found separate, so that some lakes have 

 mainly sodium chloride in solution, while others have mainly 

 compounds of sodium and magnesium sulphates. The latter 

 are called bitter-lakes. Anikin explains the difference in the 

 following way. The wind assorts the material which has been 

 crystallized out through evaporation. The common salt 

 crystallizes out first and as a firm mass, then the sulphates 

 crystallize later above this in loose powdery masses which 

 later, when left dry, are carried off by wind, the firmer 

 massas of sodium . chloride being left as a coherent deposit. 



In a supplement to Middendorff's memoir on Ferghana, 

 Schmidt gives a number of salt-analyses from which the 

 following are selected: 



1. Kara-Tjube, salt-desert. Crystalline Powder with glauber- 

 salt, gypsum, bitter-salt and clay: — 



Salts soluble in water: 74,2045 per ct. 



including: NagSO^ 62,4234 per ct. 

 CaSo^ 8,6121 — 

 MgSO^ 3,1500 — 



AlgOg 6,9.351 



2. Mojan. Efflorescence upon limestone: — 

 Salts soluble in water: 21,66i per ct. 



including: NaCl 2,742 per ct. 



Na.,SO^ 11,287 — 



CaSO^ 6,977 — 



CaCOg 47,447 — 



