48 
MANUFACTURE  OF  CARBONATES  OF  SODA. 
a  second  equivalent  of  carbonic  acid,  forming  a  bicarbonate  of 
soda  or  soda-salaratus,  when  not  pure.  The  bicarbonate  of  soda 
is  then  taken  out,  dried  and  powdered. — Sealed  Nov.  8,  1852. — 
Chem.  Gazette,  Sept.  15,  1853. 
[This  process,  thus  secured  in  England  by  letters  Patent,  is  that  of  Mr- 
Henry  Pemberton,  of  Philadelphia,  who  had  previously  obtained  a  patent  for 
it  here.  Should  the  process  be  so  far  perfected,  as  to  render  the  sulphur, 
which  escapes  as  sulphuretted  hydrogen,  available,  in  a  free  state,  the  value 
of  the  patent  will  be  greatly  increased,  and  a  present  objection  to  its  appli- 
cation will  be  removed. — Editor  Am.  Jour.  Pharm.] 
NEW  METHODS  FOR  MANUFACTURING  PURE  ACETIC  ACID. 
The  decomposition  of  acetate  of  lime  or  lead  by  means  of  sul- 
phuric acid  has  many  inconveniences,  and  there  is  danger  of  the 
product  being  contaminated  with  sulphuric  acid.  Christl  was 
therefore  induced  to  employ  hydrochloric  acid  as  a  decomposing 
agent,  and  has  found  that  when  this  acid  is  not  used  in  excess,  the 
distillate  contains  scarcely  an  appreciable  trace  of  chlorine.  A 
mixture  of  100  lbs.  of  raw  acetate  of  lime  obtained  from  the  dis- 
tillation of  wood,  and  containing  90  per  cent,  of  neutral  acetate, 
with  120  lbs.  of  hydrochloric  acid  (20°  Baume),  is  allowed  to 
stand  during  a  night,  and  then  distilled  in  a  copper  vessel.  The 
application  of  heat  requires  to  be  gradual,  in  order  to  prevent  the 
somewhat  thick  liquor  from  running  over.  The  product  of  acetic  acid 
amounted  to  100  lbs.  of  8°  Baume  ;  it  had  a  faint  yellow  color  and 
empyreumatic  odor,  which  may  be  perfectly  removed  by  treat- 
ment with  wood-charcoal  and  subsequent  rectification. 
In  order  to  obtain  the  acetate  of  lime  sufficiently  pure,  Volckel 
adopts  the  following  process  : — The  raw  pyroligneous  acid  is  sat 
urated  with  lime  without  previous  distillation.  A  part  of  the  re- 
sinous substances  dissolved  in  the  acid  are  thus  separated  in  com- 
bination with  lime.  The  solution  of  impure  acetate  of  lime  is 
either  allowed  to  stand  until  it  becomes  clear  or  filtered,*  then 
evaporated  in  an  iron  pan  to  about  one-half,  and  hydrochloric  acid 
added  until  a  drop  of  the  cooled  liquid  distinctly  reddens  litmus- 
paper.  The  addition  of  acid  serves  to  separate  a  great  part  of  the 
resin  still  held  in  solution,  which  collects  together  in  the  boiling 
*  A  part  is  distilled  off  in  a  copper  still  in  order  to  obtain  wood-spirit. 
