ON  SOME  REACTIONS  OP  OXALIC  ACID. 
345 
ON  SOME  ^REACTIONS  OF  OXALIC  ACID. 
By  J.  W."  Slater. 
The  decomposition  of  certain  chlorides  and  nitrates  by  oxalic 
acid  has  been  lately  studied.  It  decomposes  in  like  manner  the 
fluoride  of  calcium  very  readily,  hydrofluoric  acid  being  evolved 
as  if  the  fluor  spar  were  treated  with  strong  sulphuric  acid. 
Oxalic  acid  decomposes  the  phosphates  of  iron,  silver,  zinc 
and  copper,  and  the  arseniates  of  iron,  silver  and  copper.  In 
all  these  cases  the  arsenic  or  phosphoric  acid  is  set  free,  with 
formation  of  the  corresponding  oxalate. 
It  dissolves  the  sulphurets  of  iron  and  manganese,  but  not 
those  of  zinc,  cadmium,  uranium,  cobalt,  mercury  or  copper. 
This  reaction  may  be  employed  for  the  quantitative  separation 
of  iron  and  manganese  from  zinc  and  cobalt. 
Oxalic  acid  decomposes  most  of  the  chromates,  though  in  no 
case  is  chromic  acid  liberated.  The  chromate  of  zinc  is  first  dis- 
solved, forming  a  yellow  solution.  On  standing,  or  more  rapidly 
on  the  application  of  heat,  the  solution  becomes  turbid,  oxalate 
of  zinc  is  deposited  as  a  white  powder,  whilst  oxalate  of  chrome 
remains  in  solution.  The  chromates  of  bismuth,  baryta,  mer- 
cury and  lead  are  all  immediately  decomposed  by  oxalic  acid 
without  previous  solution.  The  chromate  of  lead  is  scarcely 
affected  if  it  has  been  strongly  dried. 
Chloride  of  antimony  is  decomposed  by  strong  solution  of 
oxalic  acid.  The  precipitate  is  free  from  chlorine.  It  is  only 
very  slowly  decomposed  by  boiling  water.  Glass  in  fine  powder 
is  readily  attacked  by  oxalic  acid.  Oxalate  of  lime  and  oxalates 
of  alkali  are  produced,  and  silica  is  set  free.  Silica  does  not 
appear  to  dissolve  in  oxalic  acid  under  any  circumstances.  A 
variety  of  minerals  are  more  or  less  rapidly  acted  on  by  oxalic 
acid,  yielding  products  that  still  require  examination.  The  in- 
fluence of  the  lichens  containing  oxalic  acid  is  probably  very 
important  in  effecting  the  disintegration  and  decomposition  of 
rocks,  this  acid  being,  as  we  know,  capable  of  attacking  almost 
every  class  of  saline  compounds.— London  Ohem.  Cfaz. 
