Alum  mordants  are  mostly  employed  in  dyeing
with  catechu.  "  The  salts  of  copper  with  sal-
ammoniac  cause  it  to  give  a  beonze  coLOtrE,
which  is  very  fast;  the  protochloride  of  tin,
a  BBOWNISH  YELioWj  the  perchloride  of  tin,
with  the  addition  of  nitrate  of  copper,  a  deep-
bbonze  hue  ;  acetate  of  alumina,  alone,  a
EEDDISH  BEOWN,  and  with  nitrate  of  copper,
a  EEDDISH-OLIVE  GBET ;  nitrate  of  iron,  a
DAEK-BEOWN  QEEY.  For  dyeing  a  golden
coEEEE-BEOWir,  it    has    entirely    superseded


madder ;  1  lb.  of  it  being  equivalent  to  6  lbs.
of  this  root."  (Ure.)— Dose,  10  gr.  to  30  gr.
in  solution,  in  water,  or  made  into  a  bolus,  or
sucked  as  a  lozenge.
