428  Solution  of  Lead  Subacetate.        {^SSi,  w!fm' 
The  British  directions  include  constant  stirring  of  the  boiling 
solution,  something  that  every  skilled  pharmacist  would  do  in  fol- 
lowing the  outlined  process  of  the  United  States  Pharmacopoeia. 
Now,  if  the  suggestions  cited  above  yield  good  products,  a  large 
part  of  the  time  and  attention  bestowed  upon  the  official  process 
may  be  saved. 
A  quantity  of  lead  oxide  and  acetate  sufficient  to  make  a  number 
of  samples  was  procured  and  tested  according  to  the  directions  of 
the  United  States  Pharmacopoeia.  Both  of  these  substances  were 
found  to  fulfil  all  requirements,  and  were  used  in  making  all  sam- 
ples, unless  otherwise  specified.  Distilled  water  was  always  em- 
ployed. It  was  found,  in  making  the  samples  by  cold  digestion,  that 
the  .best  results  could  be  obtained  by  placing  the  acetate  of  lead  in 
a  bottle  with  700  c.c.  of  water,  dissolving  by  agitation,  adding  to 
this  solution  the  oxide  of  lead,  and  agitating  the  mixture  until  the 
bright  color,  which  the  oxide  at  first  displayed  in  the  solution,  had 
faded  to  a  light  yellow,  a  change  usually  effected  in  five  minutes. 
Sufficient  water  was  then  added  to  bring  the  weight  up  to  1 ,000 
gm.,  and  the  bottle  was  then  placed  on  its  side,  in  order  to  present 
a  larger  surface  of  the  oxide  to  the  solvent  action  of  the  acetate  solu- 
tion, and  allowed  to  stand  for  the  allotted  time.  If  the  precaution 
to  agitate,  after  the  addition  of  the  oxide,  was  not  taken,  a  cake  of 
that  substance  formed  on  the  bottom  of  the  bottle  and  was  difficult 
to  dislodge ;  but  after  the  color  of  the  oxide  had  faded,  no  such 
cake  formed. 
The  official  method  of  estimation,  which  involves  the  use  of 
normal  sulphuric  acid  volumetric  solution  with  methyl  orange  as  an 
indicator,  was  first  tried  and  afterwards  adopted  with  a  modifica- 
tion. The  method  of  the  revision  of  1880,  using  normal  oxalic 
acid  volumetric  solution,  was  also  tried  on  a  few  samples ;  but, 
on  account  of  the  slow  settling  of  the  precipitate  of  lead  oxalate, 
it  was  abandoned. 
All  of  the  solutions  used  in  the  estimations  were  freshly  prepared 
according  to  official  directions.  The  same  proportion  of  the  solu- 
tion of  lead  subacetate  and  of  the  methyl  orange  solution  was  used 
for  each  titration,  but  the  indicator  was  not  found  to  give  satisfac- 
tory results ;  for  after  a  reddish  coloration  appeared  in  the  mixture 
under  examination,  from  1  c.c.  to  2  c.c.  of  the  volumetric  solution 
could  be  added  before  the  precipitation  of  the  lead  ceased  to  be 
