of  the  Ashes  of  Plants 
537 
pastures  grasses  having  a silicious  ash  greatly  predominate,  those 
plants  which  are  recommended  for  cultivation,  either  alone  or  in 
mixture,  and  with  the  view  of  relieving  as  it  were  the  productive 
powers  of  the  soil,  have  an  ash  in  which  silica  scarcely  occurs. 
