26 
CHEMICAL  RESEAECHES  ON  MANNITE  AND  MANNA. 
tercliloride  of  gold  gradually  a  yellowish  turbidity  (not  a  blue 
solution  like  the  aqueous  solution  of  morphia)  increasing  to  a 
brownish  flocculent  precipitate. 
It  will  be  seen  that  the  new  alkaloid  has  some  reactions  in 
common  with  morphia,  codeina  and  pseudomorphia.  An  ele- 
mentary analysis  could  not  be  made,  owing  to  the  insufficiency 
of  the  remaining  pure  snlL— Wittst,  V,  Schr.  ix.  481-489. 
J.  M.  M. 
CHEMICAL  RESEARCHES  ON  MANNITE  AND  MANNA. 
By  Dr.  Reinhard  Backhaus, 
From  the  inaugural  dissertation  of  the  author,  as  published 
in  Buchner's  K  Repert.  1860,  289-299,  we  make  the  following 
extracts  : 
The  non-reduction  by  mannite  of  an  alkaline  solution  of 
oxide  of  copper,  is  the  best  test  for  the  purity  of  the  former  ; 
this  has  been  observed  by  Berthelot,  who,  however,  does  not 
mention  the  behaviour  of  mannitan  to  such  a  solution.  Mannitan 
was  prepared  by  passing  dry  hydrochloric  acid  into  mannite 
suspended  in  alcohol,  until  a  brown  solution  had  been  effected  ; 
it  was  heated,  neutralized  with  carbonate  of  lead,  evaporated, 
exhausted  with  strong  alcohol,  re-evaporated,  and  after  redissolv 
ing  in  alcohol,  treated  with  animal  charcoal,  filtered  and  evapo- 
rated to  a  syrupy  consistence.  Diluted  and  concentrated  solu- 
tions of  this  mannitan  deoxidize  the  copper  solution. 
100  grms.  chemically  pure  mannite,  dissolved  in  250  grms. 
water  and  heated  slightly  with  250  grms.  nitric  acid  of  1-32  sp. 
gr.,  did  not  separate  any  mucic  acid  on  cooling,  which  will  be 
formed  if  the  mannite  has  not  been  entirely  purified  from  the 
mucilaginous  body  of  manna.  By  diluting  with  water  and 
digesting  for  twenty-four  hours  at  60^  C.  (140*^  F.),  the  sac- 
charic acid  is  destroyed,  and  after  half  neutralizing  v,'ith  potassa 
and  evaporating,  only  nitrate  and  binoxalate  together  with  some 
acid  saccharate  of  potassa,  crystallized  out,  but  no  bitartrate. 
Experiments  with  300  and  500  grms.  had  the  same  result. 
But  inasmuch  as  tartaric  acid,  according  to  Liebig,  appears 
to  be  formed  from  saccharic  acidj  it  is  possible  to  obtain  the 
former  by  operating  on  a  large  quantity  of  mannite. 
