CHAPTER VII 



CHEMICAL METHODS OF DETERMINING 

 ALKALI 



THERE are so many distinctly different methods of 

 making chemical analyses of soils that it is very difficult 

 to compare the work of the various investigators who have 

 studied alkali under field conditions. The wide variations 

 so often noted between results of investigators in different 

 places may be accounted for in part by the differences in 

 methods of determining the quantity of alkali present. 

 It is necessary that the method used be known before in- 

 telligent interpretation of analyses can be made. In the 

 interest of uniformity it would be highly desirable to adopt 

 standard methods. Before this can be done, it will be 

 necessary to make a careful study of the various methods 

 in order that the best one to secure uniformly accurate 

 results may be chosen. 



Preparing the Solution. Probably the greatest varia- 

 tion in methods of analyzing alkali soil is found in making 

 the soil extract. The soluble salts are dissolved with water 

 and not with the stronger dissolving agents that are used 

 in making a complete analysis of a soil, since it is the 

 water-soluble salts that come under the designation of 

 alkali. The principal variation in methods consists in 

 the relative quantities of water and soil used, the time of 

 agitation, the time allowed for settling, and the method of 

 filtering. There are certain other methods, such as ex- 



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