MANUFACTUEE OF BASIC SLAG. 217 



experiment was kept under observation. The result of these experi- 

 ments may be summarized thus : — 



1. Apart from its phosphoric acid, lime and magnesia, Etoile 

 basic slag has proved efficacious by its manganese and silica. 



2. Manganese from an agricultural point of view ought to be 

 regarded as an important constituent, influencing both the quantity 

 and the quality. 



3. It seems that silica, at least in the condition under which 

 it exists in Etoile basic slag, also acts in the same direction, but 

 that its action is weaker, less decided, and requires to be further 

 studied to be established in a general way. 



