Bui. 149, Bureau of Chemistry, U. S. Oept. of Agriculture. 



PLATE II. 



Fig. a. First crop of plants, grown 9 days in (1) distilled water; (2) distilled water + calcium 

 carbonate; (3) sol. 7, potassium sulphate; (4) sol. 8, potassium sulphate + calcium car- 

 bonate; (5) sol. 11, sulphuric acid; (6) sol. 12, sulphuric acid + calcium carbonate. 



Fig. b. First crop of plants, grown 9 days in (1) distilled water; (2) sol. 3, sodium nitrate; 

 (3) sol. 7, potassium sulphate; (4) sol. 13, sodium nitrate + potassium sulphate. 



