THE 
AMERICAN  JOURNAL  OF  PHARMACY. 
JANUARY,    1  867. 
ON  LIQUOR  MAGNESIJE  CITRATIS. 
By  John  M.  Maisch. 
During  the  discussion  on  the  Internal  Revenue  Law  which 
took  place  at  the  last  meeting  of  the  American  Pharmaceutical 
Association,  at  Detroit,  Mich.,  Prof.  Edward  Parrish  remarked 
that  the  solution  of  citrate  of  magnesia  prepared  by  the  formula 
of  the  Pharmacopoeia  would  not  keep,  but  soon  produced  a  crys- 
talline precipitate  of  neutral  citrate  of  magnesia.  Since  my 
name  was  then  mentioned  in  this  connection,  it  may  not  be  con* 
sidered  out  of  place  to  offer  some  remarks  on  this  subject. 
When  returning  to  the  practice  of  pharmacy  last  spring,  my 
attempts  to  prepare  this  solution  by  the  officinal  formula  utterly 
failed  to  produce  a  stable  solution ;  and  it  was  only  by  redu- 
cing the  amount  of  magnesia  from  120  gradually  to  100  grains, 
that  I  succeeded.  These  experiments  were  made  with  commer- 
cial light  magnesia,  of  good  quality,  containing  only  a  very 
small  amount  of  carbonic  acid,  but  free  from  iron  and  lime. 
When  105  grains  of  this  magnesia  was  employed  to  450  grains 
of  crystallized  citric  acid  and  40  grains  of  bicarbonate  of  potas- 
sa,  the  solution  would  keep  for  a  few  days,  but  then  crystals  of 
the  neutral  citrate  would  be  gradually  deposited.  These  results 
are  in  direct  opposition  to  the  statement  of  the  U.  S.  Dispensa- 
tory, which  asserts  (12th  edition,  page  1207)  that  "  solution  of 
citrate  of  magnesia  made  by  this  formula  (with  120  grains  cal- 
cined magnesia)  is  not  liable  to  the  objection  of  letting  fall  a 
granular  precipitate."    On  inquiry  among  some  of  my  friends 
