RECIPROCAL  ACTION  OF  GLYCERIN  AND  OXALIC  ACID. 
469 
I  think  if  the  cryolite  can  be  obtained  in  sufficient  quantity, 
the  importation  of  soda  ash  and  caustic  soda  into  this  country  is 
at  an  end,  or  rather  will  be.  I  fancied  our  manufacturers  were 
pretty  smart  fellows,  but  they  have  let  the  Yankees  get  ahead 
of  them  in  this  case.  All  English  manufacturers  must  look  well 
to  themselves,  as  the  Americans  are  following  very  close  at  their 
heels,  in  some  cases,  tripping  them  up, 
I  am,  &c.  H.  B. 
Philadelphia,  U.  S.,  August  30. 
London  Chem.  News,  September  22,  1865. 
THE  RECIPROCAL  ACTION  OF  GLYCERIN  AND  OXALIC 
ACID  ,  APPLICATION  TO  THE  INDUSTRIAL  PREPARATION 
OF  CONCENTRATED  AND  MONOHYDRATED  FORMIC 
ACID. 
By  M.  Lorin.* 
Formic  acid  may  be  obtained  by  the  splitting  up  of  oxalic  acid 
under  the  influence  of  glycerin.  The  preparation  by  this  reac- 
tion is  regular,  provided  water  be  added  to  the  mixture  so  as  to 
determine  the  separation  of  the  dissolved  formic  acid,  which  is 
retained  to  about  200°,  and  finally  decomposes  into  water  and 
carbonic  oxide.  Procured  in  this  way,  the  acid  contains  from  4 
to  5  per  cent,  of  real  formic  acid. 
I.  Industrial  Preparation  of  Formic  Acid  at  50  Centiemes. — 
The  mixture  of  ordinary  oxalic  acid  with  dehydrated  or  com- 
mercial glycerin  is  heated  in  a  retort.  At  75°  the  reaction  will 
commence,  and  will  be  in  full  activity  at  90°.  Simultaneously 
with  the  disengagement  of  carbonic  acid,  an  aqueous  liquid  passes, 
charged  with  formic  acid.  By  the  addition  of  a  fresh  quantity 
of  oxalic  acid — added  some  time  after  the  carbonic  acid  has  ceased 
to  be  disengaged — the  decomposition  immediately  recommences  ; 
a  liquid  again  passes  still  richer  in  formic  acid  ;  and  by  succes- 
sive additions  of  oxalic  acid,  the  richness  in  formic  acid,  of  the 
liquid  obtained  during  this  series  of  reactions,  is  always  on  the 
increase,  until  it  reaches  a  limit  which  is  precisely  that  which 
crystallised  oxalic  acid  should  give.  The  equation — 
04  H2  08.  4HO  =  C2  H2  G4  +4HO+C,  O, 
*Comptes  Rendus,  lxi.,  382. 
