SOLUTION  OF  CITRATE  OP  MAGNESIA. 
173 
For  this  purpose  40  grains  of  magnesium  oxide,  equal  to  91 
grains  of  the  carbonate,  are  replaced  by  an  equivalent  quantity 
of  either  mono  or  disodium  carbonate,  which  would  be  168  grains 
of  the  former,  or  286  grains  of  the  latter,  and  substituting  182 
grains  (equivalent  quantity)  of  magnesium  carbonate  for  the  re- 
maining 80  grains  of  the  oxide.  We  can  construct  the  following 
formula,  which  contains  the  compound  Mg^''  Na  Cg      0^.  * 
Take  of 
Citric  acid,  in  coarse  powder,       457J  grains. 
Magnesium  carbonate,  182 
Monosodium  carbonate,  168  " 
or  Disodium  carbonate,  crystallized,  286  " 
Monopotassium  carbonate,  40  " 
Essence  lemon,  a  few  minims. 
Sugar,  in  coarse  powder,  one  and  a  half  troyounces. 
Water,  sufficient. 
Dissolve  the  citric  acid  in  six  or  seven  fluid-ounces  of  water ; 
to  this  add,  gradually,  the  magnesium  carbonate,  first  rubbed 
through  a  coarse  sieve ;  when  the  solution  is  complete  add,  very 
gradually,  the  monosodium  carbonate,  or  if  the  disodium  carbo- 
nate is  used,  and  in  tolerably  large  crystals,  the  whole  of  this 
can  be  added  at  once,  then,  after  effervescence  has  ceased,  add 
the  essence  of  lemon  and  the  sugar  ;  agitate  until  the  latter  is 
dissolved,  filter  and  add  sufficient  water  to  the  filtrate  to  make  it 
measure  12  fluid-ounces ;  place  this  in  a  strong  bottle  of  appro- 
priate size ;  finally  add  the  potassium  carbonate,  and  cork 
securely. 
In  this  formula  magnesium  carbonate  is  used,  since  it  is  of 
more  uniform  composition,  much  cheaper,  and  more  convenient 
than  the  oxide.  For  various  reasons  crystallized  disodium  car- 
bonate is  preferable  to  the  monosodic.  It  was  also  found  equal- 
ly convenient  to  employ  sugar  and  essence  lemon  directly,  rather 
than  the  syrup  of  citric  acid.  The  formula  when  followed  to 
the  letter  yields  a  very  permanent  preparation.  But  to  attain 
indefinite  permanence,  and  make  surety  doubly  sure,  the  magne- 
sium can  be  reduced  one-half,  and  the  sodium  doubled. 
Chicago,  December  21,  1869. 
— QJiieago  PJiarrnacist,  Jan.,  1870. 
