584 



Journal of Agricultural Research 



Vol. X, No. II 



In Table XLV is shown the effect of sodium carbonate upon the 

 organic matter of the soil, acting, first alone in amounts from o to i 

 per cent, second in a lo per cent solution of sodium chlorid, and third 

 in a lo per cent solution of sodium sulphate. 



Table XLV. — Solubility of organic matter in sodium carbonate in the presence of lo 

 per cent solutions of sodium chlorid and sodium sulphate 



The same phenomenon is noticed as was shown in the preceding experi- 

 ment; the destructive action of sodium carbonate is checked by the 

 presence of the other sodium salts. 



In Table XLVI and figure 24 is shown to what extent the reaction of 

 sodium carbonate upon organic matter is reversible. Solutions of soil 



I 



^000 



Fig. 



.3 '.S .'O // /.? /.3 /<? 



24. — Graphs showing the organic matter dissolved from soil by sodium carbonate 

 precipitated by sodium chlorid. 



/.6 /P' /.a /.9 ciO 

 and afterwards 



were m.ade with varying concentrations of sodium carbonate and the 

 soil filtered off. Determinations of the organic matter were then made 

 upon the solutions. An excess of sodium chlorid was then' added to 

 each of the solutions, the solution boiled, and the resulting precipitate 

 filtered off. Determinations of the organic matter were again made on 

 the filtrates. These final readings represented the amount of organic 

 matter that went into solution with sodium carbonate, but which could 

 not be precipitated out with sodium chlorid. 



