IODIDE  OF  STARCH. 
439 
paste,  although  destitute  of  nitrogen,  gave  off  ammonia  during 
its  fermentation.  For  his  own  information  he  enquired  whether 
the  great  bulk  of  nitre  imported  from  India  is  made  by  the  ma- 
nurial  collection  plan  which  had  just  now  been  described? 
Dr.  Palmer  supplemented  his  previous  remarks  by  making  a 
few  statements  respecting  the  depth  at  which  water  ordinarily 
occurred  in  the  large  tracts  of  country  near  the  Himalayas,  as 
compared  with  other  localities  in  the  plains  of  the  Ganges.  There 
could  be  no  doubt  about  the  fact  that  nitre  was  collected  in  much 
greater  quantity  during  the  four  months  of  the  rainy  season  than 
at  other  times,  but  whether  the  circumstance  was  due  to  the  more 
speedy  recovery  of  the  salt,  already  formed,  by  the  solvent  action 
of  water  resulting  from  heavy  rains  penetrating  the  earth  to  a 
greater  depth,  and  by  subsequent  evaporation  becoming  reab- 
sorbed to  the  surface  ;  or  to  a  direct  influence  of  electrical  action 
in  promoting  the  nitrification,  seemed  to  him  (the  speaker)  well 
worthy  of  discussion,  and  he  was  only  glad  to  have  started  a  sub- 
ject of  so  much  interest  to  the  members  of  the  Society.  For  his 
own  part  he  now  thought  that  the  lightning  had  very  little  influ- 
ence in  contributing  to  the  formation  of  saltpetre.  In  reply  to 
Dr.  Odling  he  would  state  that  all  the  saltpetre  which  came  to 
England  was  the  produce  of  the  small  collections  brought  in  by 
the  "  Sorawallahs,"  who  for  centuries  past  and  for  many  succeed- 
ing generations  had  carried  on  this  business  in  the  Bengal  pro- 
vinces.— Lond.  Chem.  News,  July  3,  1868. 
ON  IODIDE  OF  STARCH. 
By  M.  Guichard. 
Since  its  discovery,  the  constitution  of  this  body  has  been  often 
discussed ;  according  to  some  chemists  it  is  only  a  mixture  of 
iodine  and  starch,  or  starch  tinted  by  iodine  ;  others,  on  the 
contrary,  consider  iodide  of  starch  to  be  a  definite  combination 
of  iodine  and  starch,  with  excess  of  iodine.  The  general  opinion 
is  that  the  iodide  of  starch  is  a  simple  mixture,  and  the  colorless 
iodide  is  only  starch  with  hydriodic  acid.  M.  Guichard  thought 
that  an  examination  with  the  dialyser  would  throw  light  upon 
the  question.    If  there  existed,  in  fact,  a  combination  of  iodine 
