MANUFACTURE  OF  SULPHATE  OF  QUININE. 
457 
to  preeipitate  the  alkaloids  therein,  without  being  employed  in 
excess.  The  mixture  is  then  added  to  the  other  half  of  the 
original  solution,  and  boiled  for  one  hour  if  necessary.  If  any 
grey  alkaloid  remains  undissolved,  dilute  sulphuric  acid  is  added 
cautiously,  drop  by  drop;  if  crystals  form  during  the  boiling 
more  water  is  added  to  dissolve  them.  This  operation  produces 
on  cooling  an  abundant  proportion  of  crystallized  disulphate  of 
quinine,  mixed  with  some  disulphate  of  quinidine,  and  usually 
some  sulphate  of  cinchonine.  Upon  concentrating  the  solution 
by  evaporation  and  then  allowing  it  to  cool,  a  large  proportion 
of  the  two  former  substances  may  be  recovered,  and  still  more  by 
a  second  and  third  repetition  of  the  process  of  evaporation  and 
crystallization.  The  produce  of  all  these  crystallizations  being 
mixtures  of  the  disulphates  of  the  cinchona  alkaloids,  quinidine, 
and  some  cinchonine,  should  be  purified  by  re-crystallization,  or 
other  process,  in  the  usual  manner,  so  as  to  render  the  article 
fit  for  the  market.  The  quinine,  quinidine  and  cinchonine 
remaining  in  the  mother  liquors,  should  be  extracted  by  precipi- 
tation with  a  solution  of  caustic  soda,  ammonia,  potassa,  or  other 
suitable  precipitant,  and  then  agitated  with  fusel  oil,  turpentine, 
camphene,  or  other  solvent,  as  before  described. 
The  dark  brown-red  alkaline  fluid  obtained  by  the  preparatory 
process  of  boiling  with  an  alkali,  is  now  to  be  mixed  with  the 
liquid  (containing  chloride  of  calcium)  from  which  the  alkaloids 
have  been  obtained  by  agitating  with  a  solvent,  and  the  deeply- 
colored  precipitated  carbonate  and  other  salts  of  lime  and  other 
impurities  are  allowed  to  subside,  and  should  the  liquid  be  still 
alkaline,  or  contain  excess  of  carbonate  of  soda,  a  solution  of 
chloride  of  calcium  should  be  added  to  precipitate  the  carbonic 
acid  as  carbonate  of  lime,  which  must  be  separated.  The  liquid 
separated  (still  containing  chloride  of  sodium,  the  hydrochlorates 
of  quinine,  and  other  cinchona  alkaloids)  is  then  concentrated  by 
evaporation  if  necessary,  and  heated  with  slaked  lime  or  cream 
of  lime,  and  the  precipitated  alkaloid  removed  by  the  addition  of 
fusel  oil,  turpentine,  or  other  solvent,  and  the  alkaloids  separated 
as  before  described. 
The  proportions  of  alkali,  acids,  &c,  above  indicated  are  those 
for  Peruvian  bark  of  fair  average  quality. 
The  above  process  is  also  applicable,  with  certain  modifications 
