564  Official  Lead  Preparations.  { 
Am.  Jour.  Pharm. 
November,  1897. 
the  ammonia  process,  several  conditions  were  noted,  which,  when  dis- 
regarded, are  liable  to  lead  to  error. 
Titrated  with  ^  sulphuric  acid,  using  methyl-orange  as  indicator, 
it  was  found  that  nearly  30  c.c.  were  required  before  the  orange 
color  was  changed  to  crimson,  while  in  precipitation  without  the 
indicator,  only  22  to  23  c.c.  were  required  for  13  67  grammes  of  the 
solution. 
Both  estimations  were  found  erroneous,  the  ammonia  probably 
influencing  the  reaction  with  the  indicator,  while  in  the  simple  acid 
estimation  the  fact  must  be  considered  that  ammonium  acetate, 
which  necessarily  is  present  in  the  preparation,  has  the  property  of 
dissolving  lead  sulphate. 
If  the  lead  is  completely  precipitated  by  means  of  sulphuric  acid, 
the  sulphate  removed  by  filtration  and  the  filtrate  examined,  the 
presence  of  the  metal  is  revealed  by  every  reagent,  excepting  sul- 
phuric acid. 
To  accurately  estimate  an  ammonia-prepared  Goulard's  extract 
by  means  of  volumetric  analysis,  it  is  therefore  necessary  to  employ 
a  different  precipitant. 
Volumetric  —oxalic  acid  solution  was  substituted  for  sulphuric 
1 
acid,  and  it  was  found  that  13  67  grammes  of  the  preparation 
required  23  to  24  c.c.  for  complete  precipitation. 
COMMERCIAL  GOULARD'S  EXTRACT. 
A  number  of  specimens  of  Goulard's  extract,  procured  from  vari- 
ous sources,  were  also  examined  as  to  their  specific  gravity  and 
volumetric  strength. 
In  appearance,  considerable  difference  was  noticed,  some  being 
clear  and  perfectly  colorless,  while  one  sample  was  of  a  decidedly 
yellowish-brown  color. 
All  degrees  of  intensity  in  precipitation  of  lead  carbonate  were 
also  observed. 
The  liability  of  the  preparation  to  deposit  the  carbonate  on  stand- 
ing must  be  considered  when  comparing  commercial  samples  with 
the  pharmacopoeial  standard. 
This  takes  place  even  when  every  precaution  is  employed  to  pre- 
vent the  access  of  air. 
