ON  THE  MANUFACTURE  OF  CITRIC  ACID,  ETC. 
323 
resulting  solution  of  citrate  of  potash  or  soda  be  decomposed  with 
either  salts  of  lime  or  baryta,  as  follows  : — The  lemon  or  lime- 
juice,  or  solution  containing  citric  acid,  having  been  placed  in  a 
convenient  vessel,  a  solution  of  sulphide  or  sulphides  of  potassium 
is  added,  with  application  of  heat,  until  the  whole  of  the  citric 
acid  is  converted  into  citrate  of  potash,  which  may  be  known  by 
the  solution  becoming  neutral  or  slightly  alkaline.  The  solution 
of  citrate  of  potash  thus  obtained,  being  filtered  from  the  insoluble 
impurities  and  placed  in  a  suitable  vessel,  is  decomposed  by 
means  of  sulphate  of  lime  or  a  solution  of  chloride  of  barium  or 
chloride  of  calcium,  or  of  nitrate  of  lime,  or  of  nitrate  of  baryta, 
or  chloride  of  strontium,  or  nitrate  of  strontia,  in  a  manner 
similar  to  that  at  present  adopted  for  decomposing  tartrate  of 
potash  by  means  of  sulphate  of  lime  or  chloride  of  calcium  in  the 
manufacture  of  tartaric  acid.  The  citrate  of  lime  thus  produced, 
may  be  separated  by  decantation  or  filtration,  and  the  solution 
containing  the  salts  of  potash,  viz.,  either  chloride  of  potassium, 
nitrate  of  potash,  or  sulphate  of  potash,  evaporated  in  a  conveni- 
ent evaporating  vessel.  The  salts  of  potash,  thus  obtained,  if 
mixed  with  any  impurities,  may  be  recrystallized,  so  as  to  be 
rendered  marketable. 
In  employing  the  salts  of  lime  or  baryta  to  decompose  citrate 
of  potash,  citrate  of  soda  or  citrate  of  ammonia,  solutions  either 
saturated  or  partially  so  may  be  employed,  or  sulphate  of  lime  in 
small  crystals  or  powder  may  be  used  in  the  following  proportions: 
viz.,  to  every  192  parts  by  weight  of  citric  acid,  previously  exist- 
ing in  lemon-juice  or  lime-juice,  or  contained  in  other  solutions, 
and  now  existing  as  citrate  of  potash,  citrate  of  soda,  or  citrate 
of  ammonia,  there  may  be  added  in  parts  by  weight  as  follows  : — 
246  parts  of  nitrate  of  lime,  or  318  parts  of  nitrate  of  strontia, 
or  168  parts  of  chloride  of  calcium,  or  240  parts  of  chloride  of 
strontium,  or  390  parts  of  nitrate  of  baryta,  or  312  parts  of 
chloride  of  barium,  actually  contained  in  solution  or  otherwise, 
or  258  parts  of  sulphate  of  lime. 
Dr.  Price  also  employs  sulphide  or  sulphides  of  sodium  fco 
neutralize  citric  acid.  This  may  be  employed  in  a  manner  simi- 
lar to  that  described  for  saturating  citric  acid  with  sulphate  of 
potassium,  and  after  having  separated  by  decantation  or  by  fil- 
tration the  insoluble  impurities,  he  decomposes  the  said  solution 
of  citrate  of  soda  with  sulphate  of  lime,  in  a  manner  similar  to 
