572 
Official  Lead  Preparations. 
f Am.  Jour.  Pharm. 
\  November,  1897. 
In  the  table  furnished  above  the  results  obtained  are  recorded. 
A  portion  of  the  remaining  solution  was  precipitated  by  potas- 
sium ferrocyanide  solution,  as  directed  by  the  Pharmacopoeia. 
The  remaining  solution,  acidulated  with  acetic  acid,  was  precipi- 
tated by  means  of  sulphuric  acid. 
The  filtrate  from  the  precipitated  sulphate  was  examined  for  iron 
and  calcium  in  the  usual  manner. 
COMMERCIAL  LITHARGE. 
A  good  quality  of  lead  oxide  is  indispensable  in  the  preparation 
of  Goulard's  extract  and  similar  galenicals.  Among  the  queries 
presented  to  the  A.  Ph.  A.,  the  following  is  found  : 
Commercial  litharge  is  grossly  adulterated.  What  are  the  adulter- 
ants and  in  what  quantity  are  they  present  ? 
The  writer  examined  twenty- five  samples  of  litharge,  obtained  in 
each  case,  as  far  as  known,  from  a  different  source.  Physically  the 
respective  specimens  differed  little,  but  evident  carelessness  in  keep- 
ing the  oxide,  especially  when  procured  from  paint  shops,  was 
apparent. 
The  color  varied  in  few  instances;  several  samples,  however,  con- 
tained red  lead,  which  was  revealed  by  special  examination. 
The  specimens  were  examined  according  to  the  pharmacopceial 
directions  as  to  the  amount  insoluble  in  acetic  acid. 
A  portion  of  the  acetic  solution  was  precipitated  by  means  of 
sulphuric  acid,  and  the  filtrate  examined  for  copper  and  iron  by 
means  of  ammonia  water. 
Further  examinations  for  zinc,  aluminum  and  calcium  were  also 
made  in  the  usual  manner. 
Every  sample  of  litharge  examined  contained  iron  and  calcium  ; 
aluminum  was  present  in  some,  while  copper  and  zinc  were  either 
absent  or  present  only  in  trifling  amounts. 
During  the  course  of  these  examinations  the  pharmacopceial 
directions  were  found  inadequate  for  complete  valuation  of  com- 
mercial litharge,  and  the  necessity  of  directions  for  gravimetric  or  volu- 
metric estimation  became  apparent.  The  Pharmacopoeia,  for  instance, 
gives  directions  for  the  determination  of  impurities  insoluble  in 
acetic  acid,  but  fails  to  recognize  the  liability  of  the  presence  of 
soluble  impurities  or  adulterants. 
The  logical  deduction  from  this  omission  is  the  necessary  intro- 
duction of  a  fixed  valuation. 
