176 
Citrate  of  Magnesium. 
f Am.  Jonr.  Pharm. 
I      April,  1900. 
greasy  appearance  to  the  finished  preparation.  Since  this  mixture 
contains  about  two-thirds  of  the  entire  amount  of  citric  acid  in  the 
preparation  and  there  is  an  excess  of  only  1  )/2  per  cent,  of  acid,  a 
slight  loss  in  removing  the  mass  from  the  plates  and  in  powdering 
it  results  in  an  alkaline  preparation  instead  of  an  acid  one.  I  made 
the  effervescing  salt  some  ten  years  ago  four  times  in  succession,  and 
only  the  last  lot  was  acid  in  reaction.  The  tedium  of  that  massing, 
drying  and  powdering  process  is  still  fresh  in  my  mind. 
Finally,  the  sugar,  bicarbonate  and  citric  acid  is  to  be  mixed 
with  the  powdered  mass,  and  the  whole  formed  into  a  granulated 
salt  in  the  usual  manner. 
This  yields  a  preparation  which  effervesces  copiously  when 
dropped  into  water,  but  the  last  portions  pass  into  solution  very 
slowly,  and  the  liquid  remains  opalescent  for  several  hours. 
Thus  the  increased  cost  of  the  official  preparation  is  due  not 
only  to  the  added  value  oi  the  magnesium  carbonate,  and  the  extra 
amount  of  citric  acid  required,  but  to  the  expense  of  forming  and 
powdering  the  citrate,  in  itself  a  slow,  tedious  and  difficult  opera- 
tion. Add  to  this  the  fact  that  the  final  preparation  does  not  yield 
a  clear  and  bright  solution,  and  it  is  not  to  be  wondered  at  that 
manufacturers  have  persistently  tabooed  the  preparation  and  offered 
substitutes  in  its  stead. 
The  substitutes  offered  have  been  mostly  magnesium  or  sodium 
sulphate,  combined  with  citric  or  tartaric  acid,  bicarbonate  of  soda 
and  sugar.  Some  have  contained  Rochelle  salt,  and  some  a  mixture 
of  this  with  a  sulphate. 
In  examining  a  number  of  commercial  preparations  several  years 
ago,  I  found  one  which  for  its  ingenuity  was  worthy  of  a  better 
recognition  than  that  allowed  under  a  false  label. 
Analysis  showed  this  preparation  to  have  the  following  com- 
position : 
Magnesium  citrate   2  parts. 
Citric  acid                                             ...   18  " 
Tartaric  acid  -   24  " 
Potassium  bicarbonate   16  " 
Sodium  bicarbonate   29  " 
Sugar   11  " 
To  make  100  " 
When  this  is  dissolved  in  water,  the  reaction  between  the  two  bi- 
carbonates  and  the  tartaric  acid  produces  Rochelle  salt  to  the  ex- 
