382  Ferrous  Carbonate  Preparations.  {^ugusum113, 
NOTE  ON  THE  ASSAY  OF  FERROUS  CARBONATE 
PREPARATIONS.1 
By  Frank  X.  Moerk. 
In  recently  assaying  some  samples  .of  pill-mass  and  pills  of  ferrous 
carbonate  results  were  obtained  which  show  that  it  is  impossible  to 
determine  accurately  the  quantity  of  ferrous  carbonate  in  presence 
of  organic  excipients.  Some  of  the  results  obtained  are  given  in 
the  following  table : 
la.  Ib,  II.  III. 
Pills  (293)  072  gr.       o'66gr.  —  0-54  gr. 
"    (517)  o-6ogr.         —  0-644  gr.  0*525  gr. 
Pill  Mass   3578  p.  c.      —  3810  p.  c.       32*80  p.  c. 
la.  Three  pills,  or  about  1  gramme  of  the  pill-mass,  were  heated 
with  10  c.c.  diluted  sulphuric  acid  and  50  c.c.  distilled  water  in  a 
current  of  carbon  dioxide  to  prevent  oxidation  of  the  ferrous  salt  ; 
after  complete  disintegration  resulted,  the  mixture  was  cooled  and 
titrated  with  deci-normal  Potassium  Bichromate  V.  S.  and  results  ex- 
pressed in  grains  per  pill,  or  per  cent,  in  case  of  the  mass  of  ferrous 
carbonate. 
Id.  Carried  out  as  under  la,  with  the  exception  that  about  90  per 
cent,  of  the  volumetric  solution  required  in  la  was  added  at  once 
and  then  the  titration  completed  by  the  careful  addition  of  the  volu- 
metric solution. 
II.  To  Determine  Total  Iron. — The  same  quantities  as  above  were 
boiled  for  fifteen  minutes  with  10  c.c.  hydrochloric  acid  and  50  c.c. 
water;  after  cooling,  10  c.c.  stannous  chloride  solution  (5  per  cent.) 
were  added  (to  reduce  ferric  to  ferrous  salt),  the  excess  of  stannous 
chloride  oxidized  to  stannic  chloride  by  the  addition  of  20  c.c.  mer- 
curic chloride  solution  (5  per  cent.)  and  the  mixture  titrated  with 
deci-normal  Potassium  Bichromate  V.  S.;  the  results  were  expressed 
as  above.  The  results  being  higher  than  in  I  were  at  first  inter- 
preted as  showing  the  presence  of  ferric  compounds. 
III.  To  obtain  a  check  on  II,  the  same  quantities  were  carefully 
ignited  in  porcelain  dishes  until  free  from  carbon,  allowed  to  cool 
and  then  heated  with  10  c.c.  hydrochloric  acid  with  the  occasional 
addition  of  a  few  drops  of  stannous  chloride  solution  until  the  ash 
was  perfectly  dissolved  and  a  colorless  solution  produced  (a  yellow 
1  Read  at  the  annual  meeting  of  the  Pennsylvania  Pharmaceutical  Association, 
June  1903. 
