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



PLATE VII. 



Fig. a. Crop grown 5 days in (1) distilled water; (2) distilled water -f ferric hydrate; (3) 

 potassium chlorid; (4) potassium chlorid + ferric hydrate; (5) hydrochloric acid; (6) hy- 

 drochloric acid + ferric hydrate. 



Fig. b. Crop grown 5 days in (1) distilled water; (2) distilled water + ferric hydrate; (3) 

 potassium sulphate; (4) potassium sulphate + ferric hydrate; (5) sulphuric acid 1 (6) sul- 

 phuric acid + ferric hydrate. 



