49 



earth or the like. Many experiments made with it have 

 proved contradictory. In some, it has been shown to be 

 useless for clovers, while it has proved of great service to 

 several of the grasses. Salt enhances its effects. In an 

 pxperiment made in England with potatoes, on three sepa- 

 rate acres of land of equal quality one without manure, 

 gave 160 bushels ; one manured with 30 bushels of soot, 

 yielded 19G ; and the third, which received the same quan- 

 tity of soot and seven bushels of salt, yielded 236. 



