ON  THE  MANUFACTURE  OF  TARTARIC  ACID,  ETC. 
335 
Tartrate  of  potash  having  been  obtained,  either  by  neutraliz- 
ing bitartrate  of  potash  with  sulphide  of  potassium,  or  neutraliz- 
ing bitartrate  of  potash  with  carbonate  of  lime  or  lime,  the 
solution  of  tartrate  of  potash  having  been  placed  in  any  suitable 
vessel,  sulphurous  acid  is  passed  into  it,  until  no  further  precipi- 
tation is  effected,  by  the  addition  of  a  small  quantity  of  an  acid 
stronger  than  tartaric  acid  to  the  solution.  The  precipitated 
bitartrate  o£  potash  is  separated,  and  washed  with  cold  water. 
The  decanted  or  filtered  solution  is  neutralized  with  sulphide  of 
potassium,  and  concentrated  to  about  sp.  gr.  2.000  at  212  R,  the 
tartrate  of  potash  existing  in  solutionis  decomposed  by  sulphurous 
acid,  the  resulting  bitartrate  of  potash  is  separated  as  before- 
mentioned,  and  the  mother-liquors,  being  separated  from  the 
precipitated  bitartrate  of  potash,  after  having  been  neutralized 
with  sulphide  or  sulphides  of  potassium,  [are  concentrated,  and 
the  sulphite  and  hyposulphite  of  potash  are  separated  from  the 
tartrate  of  potash  by  crystallization,  or  the  sulphite  and  hyposul- 
phite of  potash  thus  obtained  may  be  re-converted  into  sulphide 
of  potassium,  by  heating  the  dried  salts  with  small  coal,  in  a  re- 
verberatory  or  suitable  furnace,  and  the  sulphide  of  potassium 
resulting,  may  again  be  employed  for  neutralizing  and  dissolving 
impure  bitartrate  of  potash,  or  the  sulphides  or  hyposulphite  of 
potash  may  be  decomposed  with  a  stronger  acid,  and  the  liberated 
sulphurous  acid  be  employed  for  a  subsequent  operation. 
Another  improvement  of  Dr.  Price's  in  the  manufacture  #f 
purified  bitartrate  of  potash  consists  in  that  tartrate  of  potash 
and  soda  (obtained  by  neutralizing  impure  bitartrate  of  potash 
by  sulphide  of  sodium,  or  obtained  by  decomposing  tartrate  of 
potash  and  ammonia,  or  tartrate  of  potash  by  means  of  nitrate  of 
soda  or  sulphate  of  soda,  or  chloride  of  sodium,  so  as  to  obtain 
nitrate  of  potash  or  sulphate  of  potash,  or  chloride  of  potassium 
and  tartrate  of  potash  and  soda  before  described)  is  to  be  decom- 
posed by  sulphuric  acid  or  hydrochloric  acid,  in  the  proportion 
by  weight  of  50  parts  of  monohydrated  sulphuric  acid  contained 
in  solution  in  water,  or  37  parts  by  weight  of  actual  hydrochloric 
acid  contained  in  solution  in  water,  to  every  300  parts  by  weight 
of  tartrate  of  potash  and  soda  employed.  Tartrate  of  soda  and 
potash  obtained  as  above  mentioned,  being  dissolved  in  either 
Warm  or  cold  water,  and  placed  in  a  convenient  vessel,  sulphuric 
