316 Soda- Salts in Agriculture. 



residue of the filtered liquid ; this residue consequently con- 

 tained less sulphuric acid than the liquid from which it was 

 obtained. 



This view is sanctioned by the result of a direct sulphuric 

 acid determination made in the filtered liquid after contact with 

 the soil. Calculated for four deci-<;allons, 1 found 25*552 grains 

 of sulphuric acid ; and as but 24'1G() of this quantity were united 

 with lime, potash, soda, magnesium and soda, 1'386 grain of 

 sulphuric acid remained over which could only have been united 

 with ammonia. 



Like a solution of common salt, though in a minor degree, a 

 solution of sulphate of soda had the power of separating from 

 this soil, and rendering soluble, an appreciable amount of 

 ammonia. 



Experiment with Nitrate of Soda on Marly Soil. 



In my last experiment I employed a solution of nitrate of soda 

 and the same marly soil that was used in several preceding 

 experiments, 



1750 grains of this soil were shaken up in a bottle with 

 one deci-gallon of a solution containing 24"92 grains of nitrate of 

 soda. After standing three daj-s the liquid was filtered off, and 

 in it the proportions of lime, potash and soda, and of nitric acid, 

 were accuratelv determined ; the first three by the usual methods 

 of analysis, the last l)y Pugh's process. Two separate nitric acid 

 determinations gave closely-agreeing results. 



The following results were obtained in this analysis : — 



Before Filtration, After Filtration, 



the Solution contained the Solution contained 



Nitric acid 15-82 .. ., 15-715 



Soda 9-10 .. ,, 9-569 



Potash ,. ., -420 



Lime .. .. 2-408 



24-92 28-112 



This soil yielded to water alone small quantities of chloride of 

 sodium, of potash, and of carbonate of lime, Avhich accounts for 

 a little more soda being found in the liquid after contact with 

 soil than occurred in the original solution of nitrate of soda. 



Within a small fraction, the proportions of nitric acid in the 

 original solution and the liquid after filtration through the soil 

 are identical. 



It appears thus, that in this experiment neither nitric acid nor 

 soda were absorbed. 



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