256 
Action  of  Saliva  on  Starch. 
Am.  Jour.  Pharm. 
May,  1887. 
Anhydrous  inosite  has  the  composition  C6H1206,  whilst  the  crystals 
have  the  composition  06H12O6  +  2H20 ;  they  lose  all  their  water  at 
110°.  Inosite  does  not  volatilize  without  decomposition,  but  its 
molecular  weight  can  be  determined  by  Raoult's  cryoscopic  method, 
that  is,  by  determining  the  freezing  point  of  its  aqueous  solution. 
The  freezing  point  of  a  solution  of  2*5  grams  of  inosite  in  100  grams 
of  water  is  ■ — 0*29°,  whilst  the  calculated  value  for  CyE^  Oe  is — 0'27°. 
Inosite  is  only  slightly  soluble  in  cold,  but  very  soluble  in  warm 
water.  It  is  insoluble  in  alcohol,  ether  and  glacial  acetic  acid,  but 
dissolves  readily  in  dilute  acetic  acid,  from  which  it  can  be  easily 
crystallized.  It  melts  at  217°  without  carbonization,  and  boils  with 
slight  decomposition  in  a  vacuum  at  319°.  When  heated  in  the  air  it 
burns  readily.  Solutions  of  inosite  are  optically  inactive,  both  when 
freshly  prepared  and  after  they  have  been  in  contact  with  Penicillium 
glaucum  for  six  weeks.  Inosite  is  not  attacked  by  boiling  dilute  acids 
or  alkalis,  does  not  reduce  copper  solutions,  and  is  not  acted  on  by 
ammoniacal  silver  nitrate  alone,  but  in  presence  of  sodium  hydroxide 
it  yields  a  mirror  of  metallic  silver.  It  does  not  combine  with  sodium 
hydrogen  sulphite,  is  not  reduced  by  sodium  amalgam,  and  is  not 
sensibly  affected  by  halogens  in  the  cold.  When  heated  with  bromine 
and  water  at  100°,  it  yields  brown  products  precipitable  by  salts  of 
barium  and  similar  to  those  obtained  in  Scherer's  reaction.  These 
compounds  contain  no  bromine,  and  are  oxidation-products  which  can 
be  more  readily  prepared  by  the  action  of  nitric  acid. 
No  acid  containing  six  carbon-atoms  can  be  obtained  from  inosite, 
nor  will  it  split  up  into  oxy-acids  of  the  acetic  series.  It  is  neither 
an  aldehyde  nor  a  ketone,  and  contains  neither  double  bonds  nor 
lateral  chains;  hence,  it  can  only  be  a  hexhydric  hexa-secondary 
alcohol,  with  a  constitution  represented  by  the  symbol — 
OHCH<^g|gg).^ggj>CH.OH, 
which  agrees  with  its  optical  inactivity. 
ACTION  OF  SALIVA  ON  STARCH. 1 
By  E.  Bourquelot. 
Potato  starch,  free  from  glucose,  was  heateC  with  water  to  a  definite 
temperature,  cooled  down  to  the  ordinary  temperature,  and  then  mixed 
* Compt.  rend.,  104,  pp.  71-74  and  pp.  177-180.  Reprinted  from  Jour.  Chem. 
Soc,  April,  1887. 
