298         PREPARATION  OF  CITRATE  OF  IRON  AND  QUINIA. 
If,  during  the  solution,  the  temperature  rises  above  205°,  the  pro- 
cess is  very  nearly,  if  not  entirely,  arrested  before  saturation  :  and 
if  the  solution  boils,  a  precipitate  occurs  were  none  existed.  With 
the  proportions  indicated  there  is  always  a  little  residue  of  oxide 
remaining  on  the  filter,  though  the  solution  passes  with  facility. 
But  where  by  mismanagement  of  the  proportions,  as  in  the  formula 
of  the  Pharmacopoeia,  the  quantity  of  undissolved  oxide  is  con- 
siderable, it  so  clogs  the  filter  that  days  are  required  to  get  a  few 
ounces  of  dilute  solution  through  good  paper  or  muslin.  While 
decantation  is  not  well  adapted  to  the  separation  of  dark  colored 
liquids  from  their  sediment,  and  will  not  afford  a  perfectly  clear 
solution  without  great  loss. 
It  is  better  to  dry  the  salt  slowly,  and  in  thicker  lamina  than 
is  common,  as  it  thus  is  much  less  bulky.  A  two  ounce  bottle  is 
required  for  an  ounce  of  thin  scales  ;  but  after  an  ordinary  trans- 
portation, these  scales  are  found  so  broken  up  that  the  bottle  is 
only  two-thirds  filled  by  them.  The  thicker  lamina,  on  the  other 
hand,  require  much  longer  time  in  drying,  but  yield  a  finer 
preparation,  an  ounce  of  which  is  easily  put  into  an  ounce  vial. 
Quinia. 
Take  of  Sulphate  of  quinia  that  has  been  exposed 
to  a  warm,  dry  atmosphere  for  6  hours,  grs.  78. 
Sulphuric  acid,  grs-  11 J  or  6. 
Solution  of  ammonia,  f.  3  2J. 
Water,  q.  s. 
Mix  the  acid  with  f.  56  of  water,  and  dissolve  the  sulphate  of 
quinia  in  the  mixture  by  stirring.  Filter  the  solution  if  neces- 
sary ?  and  then  add  the  solution  of  ammonia,  and  stir  for  ten 
minutes.  Throw  the  whole  upon  a  thick  strainer  and  wash  with 
a  small  continuous  stream  of  water  till  the  washings  give  no 
cloudiness  with  solution  of  chloride  of  barium.  Allow  the 
magma  to  drain  to  the  consistence  of  a  curdy  paste  and  then 
transfer  it  to  a  vessel,  or  to  the  solution  of  citrate  of  iron  as  it 
comes  from  the  filter. 
I  have  weighed,  at  different  times,  the  contents  of  14  bottles 
of  the  sulphate  of  quinia  of  Messrs.  Powers  &  Weightman,  of 
Philadelphia,  and  found  them  to  vary  from  432  to  4431  grains 
gach,  the  total  being  18  grains  deficient. 
The  contents  of  a  bottle  weighing  442  grains,  exposed  in  a 
