PREPARATION  OF  CITRATE  OF  IRON  AND  QUINIA.  297 
ings  may  be  omitted,  as  also,  in  case  of  great  emergency  or  bad 
filtering  paper,  the  filtration.  The  precipitate  as  soon  as  formed 
should  be  thrown  into  the  centre  of  half  a  yard  square  of  muslin 
and  squeezed  out  twice,  once  from  the  mother  liquid,  and  once 
from  clear  water.  The  antidote  can  be  efficiently  prepared  from 
four  ounces  of  the  commonest  copperas,  and  the  solution  of  the 
sulphate  of  peroxide  filtered  before  precipitation,  in  twenty-six 
minutes.  This,  however,  is  much  too  long  to  wait  for  an  antidote, 
and  is  only  recommended  as  a  substitute  in  case  the  much  better 
plan  of  Prof.  Procter  (see  this  Journal  for  March  1853),  shall 
have  been  neglected. 
Citrate  of  Iron, 
Take  of  Citric  acid  in  crystals,  grs.  330. 
Magma  of  hydrated  oxide  of  iron  from 
the  first  formula,  the  entire  yield, 
Distilled  water,  f.  34. 
Warm  the  magma  to  about  150°  in  a  six  ounce  beaker,  in  a 
water  bath,  and  in  the  same  bath  dissolve  the  citric  acid  in  the 
water  in  a  separate  vessel.  Then  add  the  acid  solution  to  the 
magma  and  stir  occasionally  for  three  hours,  maintaining  a  tem- 
perature between  140°  and  180°,  and  finally  filter  through  paper 
and  pour  the  solution  on  plates  to  dry. 
This  process  takes  the  oxide  and  acid  in  very  nearly  equiva- 
lent proportions,  and  yields  455  grains  of  dry  citrate,  or  very 
nearly  the  sum  of  the  dry  acid  (270.9  grs.)  and  the  hydrated 
oxide  (174  grs.) 
The  salt  consists  of  Peroxide  of  iron  131  grains,  or  28.8  per  cent. 
Citric  acid,  271  "  59.56  " 
Water,  53        «    11.64  " 
As  the  acid  is  tribasic,  and  the  salt  strongly  acid  in  its  ordi- 
nary reactions  ;  and  as  theperoxide  of  iron  requires  three  equ  ta- 
lents of  an  acid  to  afford  a  normal  salt,  it  follows  that  this  cit  ate 
of  iron  is  a  very  imperfect  salt,  unless  water  combines  with  its 
acid  as  a  base,  and  also  with  its  base  as  an  acid. 
The  acid  will  not  be  saturated  short  of  two  or  three  ho  irs, 
under  the  best  management  and  frequent  stirring ;  and,  therefore, 
if  at  the  end  of  such  a  period  there  is  much  turbidity  or  sedi- 
ment in  the  mixture,  it  had  better  be  left  in  a  warm  plaoe  over 
night  before  being  filtered. 
