44 
Gallisin  in  Commercial  Glucose. 
[Am.  Jour.  Pharin. 
\       Jan.,  1885. 
tating  a  concentrated  aqueous  solution  of  gallisin  by  barium  hydrox- 
ide in  alcoholic  solution,  and  is  purified  by  dissolving  the  precipitate 
in  water,  reprecipitating  with  alcohol,  and  washing  with  ether.  The 
pure  substance  readily  absorbs  carbonic  anhydride,  is  slightly  alkaline, 
and  reduces  Fehling's  and  Knapp's  solutions.  It  loses  its  water  of 
combination  over  sulphuric  acid. 
Hexacety  I  gallisin  is  formed  by  heating  gallisin  with  acetic  anhy- 
dride for  two  and  a  half  hours  at  130-140°  under  pressure.  The 
resulting  brown  mass  is  soluble  in  alcohol,  and  after  driving  off  the 
excess  of  acetic  anhydride  on  the  water-bath,  may  be  purified  by  boil- 
ing with  charcoal  ;  the  acetyl-derivative  is  obtained  on  evaporation  of 
its  alcoholic  solution  as  a  colorless  glass-like  mass  of  the  formula 
C,2  HjgOjo  Acg.  It  is  insoluble  in  water,  but  soluble  in  alcohol  and 
similar  solvents.  If  gallisin  be  heated  for  several  hours  at  170-180° 
with  an  excess  of  acetic  anhydride,  it  is  decomposed  with  formation, 
amongst  other  products,  of  ethyl  acetate. 
Gallisin-jjotassium,  Ci2H23KOio,  is  precipitated  from  an  alcoholic 
solution  of  hexacety Igallisin  by  boiling  it  with  alcoholic  potash,  ethyl 
acetate  being  formed  simultaneously.  It  is  a  hygroscopic  powder 
soluble  in  water,  with  alkaline  reaction.  In  a  similar  way  a  precipi- 
tate of  gallisin-lead  may  be  obtained,  C\2ll22PbOio-|-PbO. 
Conversion  of  Gallisin  into  Grape-sugar. — Equal  parts  by  weight  of 
gallisin  and  oxalic  acid  were  heated  on  the  oil-bath  at  103°  for  two  to 
three  hours.  On  separating  the  oxalic  acid  with  lime  and  evaporating 
the  solution,  a  thick  sweet  syrup  was  obtained  which  in  a  few  days 
formed  a  crystalline  mass  of  glucose.  The  whole  of  the  gallisin,  how- 
ever, could  not  be  converted  into  glucose ;  by  the  prolonged  action  of 
oxalic  acid  on  an  aqueous  solution  of  gallisin,  it  becomes  yellow,  and 
smells  strongly  of  caramel. 
Oxidation  of  Gallisin. — On  pouring  a  solution  of  100  grams  gallisin 
in  50  cc.  water  into  400  grams  strong  nitric  acid,  a  powerful  reaction 
takes  place,  and  the  solution  becomes  heated  to  boiling,  with  evolution 
of  nitrous  fumes.  On  cooling,  neutralizing  with  potash,  and  afterwards 
strongly  acidifying  with  acetic  acid,  an  acid  potassium  salt  crystallizes 
out  in  beautiful  groups  of  white  needles  soluble  in  hot  water  but 
sparingly  in  cold.  About  20  grams  of  these  were  obtained  and  the 
results  of  analysis  agreed  with  the  formula  CgHgKOg.  From  this  acid 
salt  a  neutral  silver  salt,  C(5H8Ag208,  was  prepared,  and  from  the  lead 
salt  by  the  action  of  sulphuretted  hydrogen  the  free  acid  was  obtained 
