ON  THE  MANUFACTURE  OF  CITRIC  ACID,  ETC.  321 
ON  THE  MANUFACTURE  OF  CITRIC  ACID,  CITRATE  OF  LIME, 
CITRATE  OF  BARYTA,  &c  * 
In  the  ordinary  method  of  manufacturing  citric  acid,  lime-juice 
is  saturated  with  chalk,  and  the  insoluble  citrate  of  lime,  thus 
formed,  is  decomposed  by  sulphuric  acid ;  citric  acid  is  thus  set 
at  liberty.  In  this  process  the  mucilaginous  and  other  organic 
matters  contained  in  the  lime-juice,  are  to  a  great  extent  precipi- 
tated with  the  citrate  of  lime.  These  foreign  matters,  on  the 
subsequent  decomposition  of  the  citrate  of  lime  by  sulphuric  acid, 
contaminate  the  solution  of  citric  acid  obtained,  and  render  it 
necessary  for  the  manufacturer  to  have  recourse  to  a  great  num- 
ber of  crystallizations,  in  order  to  procure  the  whole  of  the  citric 
acid  in  a  marketable  state. 
In  order  to  destroy  much  of  this  mucilage  and  other  organic 
matter,  it  has  been  recommended  to  bleach  the  washed  citrate  of 
lime  by  exposure  in  shallow  vessels  to  the  action  of  the  sun's  rays, 
covered  by  a  weak  solution  of  chloride  of  lime.  In  a  few  hours, 
it  is  stated,  decoloration  takes  place,  with  the  destruction  of  much 
of  the  foreign  matter  previously  mixed  with  the  citrate,  and  thus 
much  of  the  after  labor  and  expense  of  repeated  crystallization 
is  saved  to  the  manufacturer. 
Dr.  Price's  new  process  consists  in  combining  the  citric  acid 
contained  in  lemon  or  lime-juice,  or  other  impure  solution  of 
citric  acid,  with  potash,  soda,  or  ammonia,  so  as  to  obtain  soluble 
citrates,  and  after  separating  any  insoluble  impurities  which  may 
be  present,  or  which  may  rise  in  neutralization  from  the  said 
neutral  solution  by  filtration  or  decantation,  he  decomposes  the 
said  solution  with  salts  of  lime,  baryta,  or  strontia,  so  as  to  obtain 
pure  or  nearly  pure  citrate  of  lime,  or  citrate  of  baryta,  or  citrates 
of  strontia,  and  ammonia,  or  salts  of  ammonia,  or  salts  of  potash 
or  of  soda.  The  citrate  of  lime,  or  citrate  of  baryta  or  strontia, 
is  decomposed  by  sulphuric  acid  in  the  usual  manner,  the  citric 
acid  crystallized,  and  the  ammonia,  or  salts  of  ammonia,  or  salts  of 
potash  or  of  soda,  contained  in  the  solution  from  which  the  citrate 
of  lime  has  been  precipitated,  maybe  recovered  by  crystallization  or 
otherwise. 
The  mode  of  procedure  in  carrying  out  this  process  is  as  follows : 
*  By  the  Editor  of  the  London  Pharmaceutical  Journal. 
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