•456  ACTION  OF  BICHLORIDE  OF  TIN  ON  STARCH. 
observation,  which  was  made  by  Rochleder,  has  led  to  the  fol- 
lowing researches  being  made  by  M.  Payr. 
On  mixing  starch  with  bichloride  of  tin  in  a  mortar,  the 
starch  is  almost  immediately  dissolved ;  a  slight  pitchy  residue 
forms  in  the  solution,  which  may  be  separated  by  decantation. 
After  having  filtered  the  liquid  portion,  and  having  added 
anhydrous  alcohol,  an  abundant  precipitate  is  produced,  of  a 
brilliant  white,  which,  washed  with  anhydrous  alcohol,  and  dried 
in  vacuo  over  sulphuric  acid,  is  found  to  be  composed  in  100 
parts  of: 
0  2344  23-20 
H  4-11  4.16 
0  .  .  .  33.81  33-97 
Sn.  38-67  38-50 
On  decomposing  this  matter  by  a  current  of  sulphuretted- 
hydrogen  a  limpid  liquid  is  produced,  which  is  converted  in 
vacuo  into  a  white  friable  mass,  which  the  author  found  to  be 
formed  of:-— 
0      .        .  40-90 
H      .       .  5-67 
O      .       .  52-43 
Whence  he  deduces  the  following  formula 
C24H23Q23 
By  treating  starch  with  bichloride  of  tin  at  100°C.  (212°F.) 
a  starch  paste  is  obtained  which  afterwards  liquifies  ;  alcohol 
separates  from  it  a  white  compound  containing  :• — 
C  15-56  15-44 
H  3-05  3-30 
O  24-31  24-18 
SnO    .      .       .       57-08  57-08 
The  precipitate  which  absolute  alcohol  produces  in  this  solu- 
tion made  with  the  aid  of  heat  amounts  to  scarcely  one-fifth 
part  of  that  formed  with  the  solution  made  without  heat. 
The  compound  C24H2e023,  obtained  with  the  salt  made  without 
heat  is  not  starch,  for  it  is  soluble  in  water,  and  is  not  turned 
blue   by  iodine.      Neither  is  it  dextrine  or  glucose ;  but, 
under  the  influence  of  the  weak  acids,  if  is  readily  converted 
into  the  latter. 
