Am.  Jour.  Pharm. 
Feb.,  1875. 
}        Examination  of  Citrates,  etc.  63 
Swift  and  Bro.  Effervescing  Citrate  of  Magnesia." — Qualitative  : 
Sodium,  carbonic  anhydryde^  tartaric  acid,  sugar,  a  trace  of  sulphuric 
acid.  No  magnesium  or  citric  acid.  Quantitative,  from  i  gram  : 
lead  tartrate,  0.970  gram,  equivalent  to  0*410  of  tartaric  acid  ;  sodium 
sulphate,  0*372,  equivalent  to  0*277  anhydrous  sodium  carbonate  ; 
carbonic  anhydride,  0*050.  As  0*277  ^^7  sodium  carbonate  furnishes 
0*105  carbonic  anhydride,  it  follows  that  y^^f-  of  the  sodium  has 
become  tartrate  during  and  after  manufacture.  The  article  as  pur- 
chased then  stands  very  nearly  as  follows  : 
Sodium  carbonate,  .  o'i32) 
J-       ^    ^    ^  c    \                     \  Sodium  carbonate,  .        .  0-277 
Sodium  tartrate,  .  .        czos  V  representmg ... 
r-r    ^    •         \  i  Tartaric  acid,      .        .  o*aio 
1  artaric  acid,  .  .        .    0*205  J 
Sulphuric  acid  (a  trace),  | 
Sugar,-  water,  etc.,         J  ° 
I'OOO 
(0*277  sodium  carbonate  would  neutralize  0*392  of  tartaric  acid  ; 
hence  the  analysis  shows  an  excess  of  only  0*018  of  acid,  or  four  per 
cent,  of  the  whole,) 
2.  Nichols  and  Co.,  ''Effervescing-  Citrate  of  Magnesia." — Oual- 
itative :  Magnesium,  sodium,  sulphuric  acid,  tartaric  acid,  carbonic 
anhydride,  sugar.  The  results  of  the  quantitative  work,  placed  in  the 
form  in  which  the  ingredients  were  probably  taken,  were  as  follows  : 
Magnesium  sulphate  (anhydrous),         .        .        .        .        .        .  o"i22 
Sodium  carbonate  (dried),        .......  0*242 
Tartaric  acid,       ..........  0*430 
Sugar,  water,  etc ,     .        .       .       -       .       ,       .       .        .  0*206 
(The  carbonic  anhydride  was  not  determined,  and  0*342  of  sodium 
bicarbonate  may  have  been  used  instead  of  the  0*242  of  normal  car- 
bonate, leaving  o*io6  of  sugar,  etc.  The  tartaric  acid  is  0*038,  or 
nearly  nine  per  cent,  in  excess  of  that  required  to  neutralize  the 
sodium.) 
3.  Billings,  Clapp  and  Co.,  "Magnesia  Aperient."  Qualitative: 
Magnesium  sulphate,  sodium  carbonate  or  bicarbonate,  potassium 
(bicarbonate  or  sodio  tartrate  .?),  tartaric  acid,  sugar. 
4.  W.  J.  Gordon's  "  Citrate  of  Magnesia." — A  neutral  magnesium 
citrate,  dissolving  with  difficulty  (not  effervessing). 
5.  Tarrant's  " Effervescing  Seltzer  Aperient." — Qualitative:  Mag- 
