This  compound  is  formed  when  moist  chlorine  is  passed
through  the  oil  of  bitter  almonds.  Hydrated  benzoic  acid  is
formed,  which  unites  with  the  unchanged  hyduret.  The  action
of  moist  chlorine  in  producing  hydrated  benzoic  acid  is  as  fol-
lows :  Bz  H  +  2  H  0  -f-  CLs  =  2  H  Cl  +  Bz  0,  H  0.  The  new
compound  is  crystalline,  insoluble  in  water,  soluble  in  alcohol
and  ether.  It  is  volatile  without  decomposition.  An  alcoholic
solution  of  potash  dissolves  it,  and  converts  it  into  benzoate  of


7.  Hippuric  Acid.     Cis  N  Hs  Os  +  H  0.
This  acid  is  found  in  very  considerable  quantity  in  the  urine
of  herbivorous  animals,  such  as  the  horse  and  cow,  more  especially
when  stall-fed.  It  has  also  been  lately  discovered  by  Liebig  in
human  urine.  It  is  easily  obtained  by  boiling  down  to  a  small
bulk  the  fresh  urine  of  the  horse  or  cow,  after  adding  an  excess
of  milk  of  lime,  and  acidulating  with  hydrochloric  acid.  On
standing,  the  liquid  deposits  brown  crystals  of  hippuric  acid,
which  may  be  decolorised  by  boiling  with  excess  of  lime,  and
enough  of  boiling  water  to  dissolve  all  the  hippurate  of  lime,  and
adding  to  the  strained  solution  hydrochloric  acid  in  excess,  when
the  hippuric  acid  is  deposited.  A  repetition  of  this  process  renders
it  quite  white.  If  benzoic  acid  be  present,  it  is  removed  by  ether.
