'^'^  jln"^885'™" }        Colloidal  Derivatives  of  Ferric  Hydroxide.  45 
as  a  thick,  acidj  uncrystallizable  syrup,  soluble  in  water  and  alcohol 
but  insoluble  in  ether.  On  distilling  the  ammonium  salt,  besides  am- 
monia, pyrroline,  etc.,  a  sublimate  was  obtained  which  is  soluble  in 
water,  alcohol,  and  ether,  and  at  present  is  under  investigation. 
Action  of  Heat  on  Gallisin. — On  heating  gallisin  in  a  current  of 
hydrogen  gas  on  the  water-bath  at  65°,  carbonic  anhydride  and  water 
are  given  oif,  and  at  100°  it  melts  to  a  thick  amber-colored  syrup ; 
17'2  per  cent,  of  water  (4  mols.  =  18  per  cent.)  and  13'7  per  cent,  of 
carbonic  anhydride  (1  mol.  =  13'4  per  cent.)  were  given  off.  This 
syrup  has  many  of  the  properties  of  gallisin,  as  has  also  its  barium 
compound,  which  is  found  on  analysis  of  the  barium  derivative  to  have 
the  formula  (Q^^^f)^^^.  This  may  mean  that  gallisin,  when  heated, 
gives  up  water  and  carbonic  anhydride,  but  when  the  resulting  sub- 
stance is  treated  with  water  the  water  is  again  taken  up,  and,  as  the 
barium  derivative  shows,  a  compound  is  formed  containing  1  mol.  of 
carbonic  anhydride  less  than  gallisin. 
The  authors  succeeded  also  in  preparing  pure  gallisin  from  a  wine 
which  had  been  prepared  by  GalFs  process  in  1873,  and  identified  it 
by  the  above  reactions  and  by  analysis.  In  conclusion,  the  authors 
mention  that  a  physiological  investigation  of  gallisin  is  being  made, 
and  already  it  has  been  found  by  numerous  trials  that  there  is  no 
direct  or  indirect  unwholesomeness  in  the  use  of  gallisin  or  of  the 
glucose  which  is  formed  along  with  it. — Ber.,  xvii.,  pp.  1000-1015; 
Jour.  Chem.  Soc,  pp.  981,  982  and  983,  October,  1884. 
COLLOIDAL  DERIVATIVES  OF  FERRIC  HYDROXIDE. 
By  E.  Grimaux. 
When  potassium  hydroxide  is  added  to  a  mixture  of  glycerol  and 
ferric  chloride,  a  precipitate  is  formed  soluble  in  excess,  and  the  solu- 
tion has  the  characteristic  properties  of  the  colloidal  solutions  previously 
described  (coagulation,  etc.).  The  tendency  to  coagulate  is  diminished 
by  the  presence  of  a  large  amount  of  glycerol,  and  increased  by  the 
presence  of  sodium  chloride  or  of  potash  in  excess.  If  the  proportion 
of  glycerol  is  very  large,  coagulation  is  entirely  prev^ented.  When 
solutions  rich  in  glycerol  are  dialysed,  they  first  lose  their  excess  of 
potash,  then  their  excess  of  glycerol,  and  become  coagulable  by  heat, 
and  finally  they  form  a  firm  thick  jelly  containing  glycerol,  ferric 
