IRON 51 



its main usefulness to this property. It is a powerful 

 alkali, its ions are very active. Furthermore, experiment 

 indicates that calcium and potassium ions are both 

 needed to neutralize each other. The compounds of 

 potassium are freely soluble and hence the more able to 

 display their molecular activity. 



Iron is equally indispensable. In some way now quite 

 unguessed and unproved, it takes its part in the meta- 

 bolic processes of the organism, being in plants as in 

 animals intimately if not directly connected with the 

 formation of coloring matters. Thus, iron is used in 

 medicine to assist in the alleviation of anaemic conditions 

 in human beings, restoration to health being indicated 

 by heightened color; and in plants blanching may often 

 be cured by administering iron. 



