568 



Journal of Agricultural Research 



Vol. X, No. II 



Table XXXII. — Solubility of organic matter in solutions of mixtures of sodium chlorid 



and sodium sulphate 



It will be seen by reference to the graphs that the curves for the 

 untreated soil follow very closely the curves of the soil to which 2 per 

 cent of calcium carbonate had been added. This seems to indicate that, 



S /o /cr ^o ^s '30 >3S <'o f^s so -ss GOf- 



/=ir/? CSAfT- A/aC/- 

 Fig. 19. — Graphs showing the solubility of organic matter in soil in solutions of sodium chlorid. 



although there was not enough calcium carbonate in the untreated soil 

 to visibly effervesce with acid, still there was enough to react with the 

 sodium salts and to form sodium carbonate until equilibrium was reached, 

 and to all purposes it was a calcareous soil. The difference in the solu- 

 bility of the organic matter in the acid-treated soil and the lime or 

 untreated soil is a fair measure of the action of the sodium salts upon 

 calcium carbonate with the formation of sodium carbonate. 



It seems from these results as if the normal carbonate was being formed, 

 although it was impossible to detect it by phenolphthalein, except in one 



