Soda-Salfs in A(jricidlurc. 315 



3500 grains of soil, and four deci-gallons of solution of sulphate 

 of soda were left in contact for four days, and the experiment 

 carried out precisely as before. 



The analysis of the filtered liquid, after contact with soil, 

 calculated for four deci-gallons, gave the following results : — 



Organic matter 3-240 



Soluble silica -120 



Oxides of iron and alumina and traces of pliosplioric acid -lOO 



Sulphate of lime 1*714 



Sulphate of magnesia -042 



Sulphate of potash -812 



Chloride of sodium -GHO 



Sulphate of soda 39-696 



47-004 

 By direct evaporation of two deci-gallons of the clear solution, 



23*45 grains of solid residue, dried at 300° Fahr., were obtained ; 



this gives 46*90 for the total solution, and agrees very closely 



with the sum-total of the constituents found in the analysis of 



the dried residue. 



This soil, under precisely similar conditions, absorbed less 



soda than the marly soil : — 



Sulphate of „ i 



Soda. •^"'''^- . 



Before the experiment, 4 deci-gallons of liquid) .. r,nr^ -in ^i- 



contained .. f ^^''^''^ = ^^'^'^' 



After contact with 3500 grains of soil .. .. 39-696 = 17-329 



Difference 5-234 = 2-288 



Accordingly 1000 grains of this sandy sterile soil absorbed only 

 0-653 of soda. 



The sulphuric acid in the liquid after filtration through the soil 

 is distributed as follows : — 



22-364 grains arc united with soda 

 *373 „ ,, potash 



•421 „ „ magnesia 



1*008 „ „ lime 



24-166 grains of sulphuric acid altogether. 



Before filtration the solution contained 25*312 grains of 

 sulphuric acid; consequently 1*146 grain was not recovered in 

 the fixed and heated residue. 



I have pointed out already that this soil contained ammonia in 

 a state of combination, which enabled me to expel readily an 

 appreciable quantity by distillation with caustic potash, A 

 portion of sulphuric acid, originally united with soda, evidently 

 passed into the filtered liquid in combination with ammonia. As 

 sulphate of ammonia, like all salts of ammonia, is volatile at a 

 high temperature, none could lie retained in the strongly-heated 



