IRON AND ALUMINUM SALTS ON CLOVER SEEDLINGS. 127 



9. Nutrient solvition+1 c-c- '^io molecular Al sol.+CaS04. 



10. Nutrient sclution4" 10 c.c. Mo molecular sol. FeS04=22 p. p.m. of Fe. 



11. Nutrient solution+10 c.c. VlO molecular FeS04 sol.+CaCO.i. 



12. Nutrient solution + 10 c.c. Vio molecular FeS04 sol.+CaS04. 



13. Nutrient solution+5 c.c. Vio molecular FeS04 sol. =11 p. p.m. of Fe. 



14. Nutrient solution+5 c.c. Vio molecular FeS04 sol.+CaCO:;. 



15. Nutrient solution+5 c.c. Vio molecular FeS04 sol.+CaS04. 



16. Nutrient solution-i-2 c.c. Vio molecular FeSO* sol. =4.5 p. p.m. of Fe. 



17. Nutrient solution+2 c.c. Vio molecular FeS04 sol.+CaCOs. 

 IS. Nutrient solution+2 c.c. Vio molecular FeS04 sol.+CaS04. 



At the end of three days most of the plants in the higher concentrations 

 of the ferrous sulfate had died. These were replaced, but by the end of 

 the first week these too had died. This failure of the plants to make 

 a start was, I think, in part due to unfavorable weather, there being 

 practically no sunshine during this first week. The same differences as 

 indicated in the first experiment were noticed in this series. Calcium 

 carbonate counteracted the toxic influence of the aluminum salt in both 

 concentrations to a marked degree, but not entirely. In the iron-treated 

 solutions the calcium carbonate had a slightly beneficial effect on No. 

 14 (11 p. p. m. of Fe), more beneficial on No. 17 (4.5 p. p. m. of Fe), 

 but no effect on the highest concentration (22 p. p. m. of Fe). Calcium 

 suKate had no effect, the plants being similar to those in the solutions of 

 the same concentrations without the calcium salt. It was also noticed 

 that the seedlings in the solutions containing the iron and aluminum 

 salts without the addition of calcium had a tendency to have stems of a 

 reddish color. The experiment was discontinued at the end of the third 

 week, as most of the plants had died from excessive heat. An extremely 

 hot spell made it impossible to keep the greenhouse cool. 



The third experiment was a repetition of the second, with the exception 

 that the highest concentration of the ferrous salt was omitted, and a 

 more dilute one added. 



Treatment ernployed in Third Experiment. 



1. Nutrient solution 1 



2. Nutrient solution+CaCO.-; \ checks. 



3. Nutrient solution+CaS04 J 



4. Nutrient solution+2 c.c. Vio molecular aluminum sol. =43 p. p.m. of AL 



5. Nutrient solution+2 c.c. Vio molecular aluminum sol. + CaCOg. 



6. Nutrient solution+2 c.c. Vio molecular aluminum sol. + CaS04. 



7. Nutrient solution+1 c.c. Vio molecular aluminum sol. =21.6 p. p.m. of Al. 



8. Nutrient solution+1 c.c. Vio molecular aluminum sol.+CaCOs. 



9. Nutrient solution+1 c.c. Vio molecular aluminum sol.+CaS04 



10. Nutrient solution+5 c.c. Vio molecular FeS04 sol. =11 p.p.m. of Fe. 



11. Nutrient solution+5 c.c. Vio molecular FeS04 sol.+CaCO;;. 



12. Nutrient solution+5 c.c. Vio molecular FeS04 sol.+CaS04. 



13. Nutrient solution+2 c.c. Vio molecular FeS04 sol. =4.4. p.p.m. of Fe. 



14. Nutrient solution+2 c.c. Vio molecular FeS04 sol.+CaCOi;. 



15. Nutrient solution+2 c.c. Vio molecular FeS04 sol.+CaS04. 



16. Nutrient solution+1 c.c. Vio molecular FeS04 sol. =2.2. p.p.m. of Fe. 



17. Nutrient solution+1 c.c. Vio molecular FeS04 sol.+CaCOa. 



18. Nutrient solution+1 c.c. Vio molecular FeS04 sol.+CaS04. 



