556  Solution  of  Suhacetate  of  Lead.       {^VJ^l;  ^m^""' 
(C2H302)2Pb''30H2),  containing  an  indefinite  proportion  of  sesqui- 
basic,  and  none  whatever  of  the  dibasic  salt.  The  measure  of  the  ul- 
timate product  is  also  not  directed ;  but  which,  if  it  contained  only 
diplumbic  acetate,  as  is  obviously  the  officinal  intention,  should  be 
made  to  measure  4J  pints,  thus  presenting  1  troy  ounce  of  diplumbic 
acetate  in  3  fluid  ounces  of  the  solution.  Owing  to  the  unsatisfactory 
results  of  the  officinal  method,  the  writer  discarded  the  use  of  litharge 
altogether,  and  resorted  to  the  plumbic  hydrate  made  by  precipita- 
tion. As  will  be  evident,  this  modification  of  the  procedure  elimi- 
nated the  objectionable  features  by  yielding  a  definite  product,  and 
simplifying  the  operation. 
Freshly  precipitated  plumbic  hydrate  is  readily  and  completely 
soluble  in  a  warm  solution  of  the  normal  plumbic  acetate,  and  the 
compact,  curdy  character  of  the  precipitate  admits  of  its  most  easy 
and  perfect  separation  by  means  of  a  strainer  from  the  precipitating 
liquid. 
The  officinal  formula  employs  16  troy  ounces  of  normal  plumbic 
acetate,  and  9J  troy  ounces  of  semivitrified  plumbic  oxide,  and  at- 
tempts to  form  a  solution  by  boiling  the  mixtnre  with  4  pints  of  water 
for  half  an  hour.  The  second  lead  molecule  of  the  compound  to  be 
generated  is  represented  by  16  troy  ounces  more  of  normal  plumbic 
acetate.  If,  now,  16  troy  ounces  of  this  salt  be  treated  with  4|- 
ounces  of  pure  potassium  h3''drate  (free  from  carbonate)  which  is  a 
slight  excess,  the  requisite  quantity  of  plumbic  hydrate  necessary  to 
furnish  the  extra  molecule  is  precipitated. 
This  is  now  separated  with  a  muslin  strainer,  and  the  solid  resi- 
duary cake  heated  nearly  to  boiling,  with  16  troy  ounces  of  the  nor- 
mal acetate,  dissolved  in  about  3J  pints  of  distilled  water.  If  the  po- 
tassium hydrate  was  free  from  carbonate,  the  precipitate  will  dissolve 
completely,  otherwise  a  small  residue  of  plumbic  carbonate  will  re- 
main after  filtration.  This  may  be  dissolved  in  a  few  drops  of  acetic 
acid,  and  incorporated  with  the  solution.  The  liquid  strained  from 
the  precipitated  plumbic  hydrate  is  a  solution  of  potassium  acetate,, 
which  can  be  utilized  by  adding  potassium  carbonate  to  remove  a 
trace  of  lead  held  in  solution  by  the  slight  excess  of  alkali  first  used, 
the  solution  neutralized  with  acetic  acid  after  filtration,  and  evapo- 
rated to  dryness. 
The  new  formula  for  solution  of  diplumbic  acetate  is  then  as- 
follows  : 
