Jul. 149, Bureau of Chemistry U. S. Dept. of Agriculture. 



PLATE IV. 



Fig. a. Second crop of plants, grown 5 days in residual solutions (1) distilled water; (2) 

 distilled water + calcium carbonate; (3) sol. 7, potassium sulphate; (4) sol. 8, potassium 

 sulphate + calcium carbonate; (5) sol. 11, sulphuric acid; (6) sol. 12, sulphuric acid + cal- 

 cium carbonite. 



Fig. b. Second crop of plants, grown 5 days in residual solutions (1) distilled water- (2) 

 sol. 3, sodium nitrate; (3) sol. 7, potassium sulphate; (4) sol. 13, sodium nitrateand potas- 

 sium sulphate. 



