56o 



Journal of Agricultural Research 



Vol. X. No. II 



Table XX. — Reaction between sodium, chlorid and calcium carbonate in the presence of 



carbon dioxid 



Table XXI. — Reaction between mixtures of equal parts of sodium chlorid and sodium 

 sulphate, and calcium carbonate in the presence of carbon dioxid 



Table XXII. — Reaction between sodium sulphate and calcium carbonate in the presence 



of carbon dioxid 



THEORETICAL EFFECT OF A FIELD APPLICATION OF GYPSUM ON 



BLACK ALKALI 



It was long ago suggested by Dr. Hilgard that an application of gyp- 

 sum would improve soils containing black alkali. This method of re- 

 claiming alkali soils has been used a great many times, with and without 

 success. By reference to the foregoing tables and graphs, one can form 

 a definite idea of what will happen when gypsum is applied to any par- 



