50 
ON  THE   CINCHONAS  OF  COMMERCE. 
either  by  skimming  or  nitration  through  a  linen  cloth.  The  distilled 
acid  has  aspecific  gravity  ranging  between  1.058  and  1.061,  contain- 
ing upwards  of  40  per  cent,  of  anhydrous  acetic  acid.  It  is  rarely 
that  acid  of  this  strength  is  required  ;  and  as  the  distillation  is 
easier  when  the  mixture  is  less  concentrated,  water  may  be  added 
before  or  towards  the  end  of  the  distillation.  Volckel  recommends 
as  convenient  proportions — 
100  parts  acetate  of  lime, 
90  to  95  hydrochloric  acid, 
25  parts  water, 
which  yield  from  95  to  100  parts  of  acetic  acid  of  1.105  spec, 
grav.  150  litres  of  raw  pyroligneous  acid  yield  about  50  lbs.  of  acetic 
acid  of  the  above  specific  gravity. 
The  acid  prepared  in  this  way  may  be  still  further  purified  by 
adding  a  small  quantity  of  carbonate  of  soda  and  redistilling  ;  it  is 
thus  rendered  quite  free  from  chlorine,  and  any  remaining  trace  of 
color  is  likewise  removed.  The  slight  empyreumatic  smell  may 
be  removed  by  distilling  the  acid  with  abouttwo  or  three  per  cent, 
of  acid  chromate  of  potash.  Oxide  of  manganese  is  less  effica- 
cious as  a  purifying  agent. 
Although  pure  acetic  acid  may  be  procured  by  the  distillation  of 
vinegar,  the  whole  of  the  acid  cannot  be  obtained  except  by  dis- 
tilling to  dryness,  by  which  means  the  extractive  substances  are 
burnt,  and  the  distillate  rendered  impure.  In  order  to  obviate  this 
difficulty  Stein  proposes  to  add  30  lbs.  of  salt  to  every  100  lbs.  of 
vinegar  ;  the  boiling  point  is  thus  raised,  and  the  acid  passes  over 
completely. — Chemical  Gazette. 
ON  THE  CINCHONAS,  AND  THE  QUESTIONS  WHICH,  IN  THE 
PRESENT  STATE  OP  SCIENCE  AND  COMMERCE  ARE  MORE 
IMMEDIATELY  CONNECTED  WITH  THEM. 
By  MM.  A.  Delondre  and  Bouchardat. 
Rolled  Cinchona  Calisaya. — Very  thick  epidermis,  rough,  un- 
even, marked  at  distances  with  annular  fissures,  and,  in  the  inter- 
mediate space,  with  transverse  and  longitudinal  cracks,  more  or 
less  close  to  each  other,  often  anastomosed,  of  a  silvery  or  greyish 
white.    Internal  face?  purely  fibrous,  of  a  yellow  fawn,  even  tex- 
