Am.  Jour.  Pharm. } 
May,  1881.  J' 
Chemical  Notes. 
233 
stopped,  whereupon  it  was  shaken  with  some  coarsely  ground  litharge 
and  filtered,  after  which  dialysis  proceeded  satisfactorily. 
An  attempt  was  made  to  obtain  mannite  by  this  process  from  infu- 
sions of  the  roots  of  Taraxacum  deus  leonis  and  Leptandra  virginica 
and  of  the  bark  of  Canella  alba,  in  which  it  is  said  to  exist,  but  with- 
out success.  From  the  canella,  however,  about  0*25  per  cent,  of  small, 
colorless,  acicular  crystals  was  obtained,  the  character  of  which  was 
not  further  examined. 
Mannite  is  soluble  in  four  parts  of  cold  water,  three  parts  of  acetic 
acid,  and  insoluble  in  ether,  chloroform  and  petroleum  benzin.  When 
it  is  moistened  with  concentrated  siilphuric  acid  and  some  acid  chro- 
mate  of  potassium  afterward  added,  a  yellowish-green  color  is  pro- 
duced, which  changes  soon  to  a  dirty,  greenish  brown.  Dialyzed 
mannite  in  contact  with  air  assumes  a  yellowish  color,  which  deepens 
by  age.  When  perfectly  pure  it  should  not  precipitate  an  alkaline 
solution  of  cupric  sulphate  on  the  application  of  heat. 
CHEMICAL  NOTES. 
By  Prof.  Samuel  P.  Sadtler,  Ph.D. 
Inoeganic  Chemistry. — Spontaneous  Combustion  Engendered  by 
Nitric  Acid. — In  the  last  number  of  this  journal  (April,  1881,  p.  170) 
some  experiments  on  the  development  of  a  spontaneous  combustion  in 
boxes  in  which  strong  nitric  acid  had  been  spilled  upon  hay,  straw  and 
similar  organic  materials  were  narrated.  In  this  narration  the  state- 
ment was  made  that  nitric  acid  of  1*45  gravity  would  not  give  rise  to 
a  combustion.  R.  Haas  has  since  described  some  experiments  bearing 
upon  the  same  subject.  He  finds  that  when  the  hay  or  straw  is  packed 
thoroughly  so  that  no  great  air  spaces  are  left  between,  and  when  the 
acid  is  added  at  several  times  as  the  material  is  packed  in  layers,  acid 
of  1*39,  or  ordinary  commercial  nitric  acid,  can  give  rise  to  spontane- 
ous inflaming.  The  only  essential  conditions  seem  to  be  a  compact 
packing  so  that  the  heat  of  the  reaction  is  not  dissipated,  and  a  thorough 
saturation  of  the  material  with  the  acid.  In  cases  of*  accidents  from 
breaking  of  nitric  acid  flasks  in  transport  these  conditions  are  often 
present,  and  hence  the  resulting  fires. — Ber.  der  Chem.  Ges.,  xiv.  p.  597. 
Preparation  of  Ferrlcyanide  of  Potassium. — K.Seuberlich  has  tested 
the  conditions  under  which  ferrocyanide  of  potassium  is  changed  by 
the  action  of  lead  peroxide  in  alkaline  solution  into  the  ferricyanide  of 
