Gallisin  in  Commercial  Glucose.  43 
crumbling  yellow-gray  mass,  which  by  pounding  in  a  mortar  with  a 
mixture  of  absolute  alcohol  and  ether  can  be  obtained  as  a  gray  powder. 
This  powder  may  be  purified  by  dissolving  it  in  water,  repeating  the 
above  treatment,  and  drying  over  sulphuric  acid. 
Gallisin  when  viewed  under  the  microscope  is  found  to  be  amor- 
phous and  without  any  characteristic  structure.  It  is  intensely  hygro- 
scopic, more  so  than  calcium  chloride,  but  yields  no  definite  compound 
with  water.  It  is  insoluble  in  ether,  chloroform,  and  benzene,  very 
sparingly  soluble  in  glacial  acetic  acid  and  in  absolute  alcohol,  but 
slightly  more  so  in  methyl  alcohol,  and  in  this  it  differs  from  glucose 
which  is  readily  soluble.  It  dissolves  when  boiled  in  a  mixture  of 
glacial  acetic  acid  and  absolute  alcohol,  bat  it  is  precipitated  from  this 
solution  by  ether.  In  concentrated  aqueous  solution,  it  has  an  acid 
reaction  to  litmus-paper ;  and  undergoes  no  change,  either  by  heat  or 
Avhen  treated  with  lead  acetate,  mercuric  nitrate  or  chloride,  ferric 
chloride,  tincture  of  iodine,  or  calcium  or  barinm  chloride.  Barium 
hydroxide  precipitates  a  small  quantity  of  a  white  barium  compound. 
With  silver  nitrate,  it  undergoes  no  change  until  it  is  heated  or  am- 
monia is  added,  when  metallic  silver  is  precipitated.  It  rapidly  reduces 
potassium  permanganate,  especially  in  slightly  alkaline  solution,  with 
separation  of  peroxide  of  manganese.  Potassium  dichromate  in  dilute 
acid  solution  is  also  rapidly  reduced.  Fehling's  and  Knapp's  solutions 
are  reduced  by  it  (in  this  it  differs  from  dextrin),  and  0*05  g.  glucose 
are  equal  to  0*109784  g.  gallisin  in  reducing  power.  A  concentrated 
solution  of  gallisin  prevents  the  precipitation  of  iron  salts  by  ammonia 
or  caustic  alkalis.  With  acetic  anhydride,  it  gives  an  acetyl  com- 
pound, and  it  is  converted  into  glucose  by  treatment  with  dilute  mineral 
acids  on  the  water-bath.  On  treating  an  aqueous  solution  with  fresh 
yeast  it  is  not  fermented,  nor  does  it  undergo  lactic  fermentation,  but 
if  a  dilute  aqueous  solution  is  allowed  to  stand  for  a  time  it  decomposes 
with  formation  of  a  mouldy  fungus.  At  100°  it  gives  off  water  and 
carbonic  anhydride.  It  has  a  slightly  sweet  taste  at  first,  but  in  time 
becomes  insipid.  A  solution  of  gallisin  turns  the  plane  of  polarization 
to  the  right,  and  this  power  increases  according  to  the  dilution  of  the 
solution.  A  very  pure  white  specimen,  when  analysed  with  every  care 
to  prevent  access  of  moisture,  was  found  to  contain  43*50  per  cent.  C 
and  7*36  per  cent.  H,  and  these  results  lead  to  the  formula  C^e^l^f^xo 
(C,  43-9  :H,  7-32). 
Gallisin-harium,  Ci2H22B:iO,o+ 3  HgO,  may  be  obtained  by  precipi- 
