434 " DESCRIPTIVE GEOLOGY. 



A drop of the water, without concentration, gave spectra of potassa 

 and lithia; a faint reaction for bromine and boracic acid was also obtained. 



In this connection, it is interesting to note an analysis of the surface- 

 soil from a mud or alkali flat, not far from the lake-shores, between Salt 

 Lake City and Black Rock Point. The material collected contained 16.40 

 per cent, of soluble matter, composed as follows: 



Calcium 6.16 6.28 



Magnesium 2.22 2.16 



Sodium 29.62 29.45 



Potassium --- 0.46 0.46 



Chlorine 57.97 57.83 



Sulphuric acid 3.72 3.44 



Oxygen equiv. S O3 0.74 0.68 



100.89 100.10 

 or, theoretically combined: 



Chloride of sodium 71.43 71.05 



Chloride of magnesium 8.80 8.55 



Chloride of potassium 0.88 0.87 



Chloride of calcium 11.94 12.11 



Sulphate of lime 6.31 5.84 



Excess of sodium 1.53 1.68 



100.89 100.10 



In composition, these salts show a remarkable analogy to those of the 

 waters of Salt Lake, from which, at no very remote period, they must have 

 proceeded. The relative proportions of chlorides of calcium and magnesium 

 remain the same, but a portion of each has been replaced by the lime of the 

 soil. It is noticeable that in this soil, as in that of the Great Desert, the 

 alkaline chlorides are present in great abundance, but the alkaline sul- 

 phates are wanting. It is interesting that in the waters of a lake containing 

 so much mineral matter in solution, and which lies in a region of limestone 

 rocks, so little lime should be found in solution as the above analysis shows. 

 As the sulphates and carbonates of lime are, however, easily precipitated, 

 it is probable that, in the solution presented by the waters of Salt Lake, they 



