OVER-IRRIGATION AND ALKALI 



391 



PERCENTAGE COMPOSITION OF ALKALI CRUSTS 



In the first sample from New Mexico, sodium sulfate, 

 or Glauber's salt, predominates; in the second, from 

 Wyoming, magnesium sulfate, or Epsom salts, is most 

 prominent; hi the third, from Utah, calcium sulfate, or 

 gypsum, predominates; in the fourth, from Colorado, 

 sodium nitrate, or niter, predominates, and hi the fifth, 

 from Utah, sodium chloride, or common salt, predom- 

 inates. 



Between the extreme compositions shown hi the above 

 table, all possible variations occur. It is impossible to 

 lay down any rule for the composition of alkali, unless 

 the source is known. The following, analysis of a Cali- 

 fornia sample also shows the gpmplex composition of 

 alkali : 



Potassium sulfate 3.95 



Sodium sulfate 25.28 



Sodium nitrate 19.78 



Sodium carbonate 32.58 



Sodium chloride 14.75 



Sodium phosphate 2.25 



Ammonium carbonate. . 1.41 



Total . 100.00 



