^m'juner;iP894arm'}  Lead  in  Tartrates.  297 
revealed  an  abundance  of  lead  in  a  soluble  form  upon  the  addition 
of  ammonium  sulphide  solution. 
On  prolonged  contact,  as  the  lead  passes  into  solution,  the  mixture 
becomes  alkaline,  changing  the  color  of  red  litmus  as  well  as  turn- 
ing red  with  phenolphtalein  test  solution.  This  would  indicate  the 
liberation  of  an  alkali  hydrate. 
The  same  observation  was  also  made  with  the  citrates  of  lithium 
and  potassium. 
POTASSIUM  TARTRATE. 
This  salt  is  rarely  employed  in  medicine,  not  being  official. 
In  the  Pharmacopoeia  of  1880  it  was  used  in  the  preparation  of 
Fehling's  solution. 
Of  the  commercial  tartrates  examined,  this  salt  was  the  only  one 
which  showed  the  presence  of  an  appreciable  amount  of  lead  in  a 
soluble  form.  Particles  of  metallic  lead  ivere  not  found.  The  three 
samples  examined  gave  decided  reactions  for  lead. 
LEAD  TARTRATE, 
If  the  conjecture  is  correct,  that  in  the  latter  salt  the  lead  exists 
in  the  form  of  tartrate,  it  may  be  of  interest  to  inquire  into  the 
character  of  this  compound. 
Trials  to  determine  its  nature  were  made  similar  to  those  described 
in  connection  with  citrate  of  lead. 
Several  forms  of  lead  tartrate  exist  according  to  Watts'  Dictionary 
of  Chemistry. 
To  determine  the  solubility  of  this  salt  it  was  first  attempted  to 
prepare  the  same  by  saturating  a  concentrated  aqueous  solution  of 
tartaric  acid  with  lead  carbonate,  keeping  the  mixture  at  the  boiling 
point  during  saturation. 
The  mixture  was  allowed  to  stand  some-  time  before  it  was 
examined. 
The  tartaric  filtrate,  separated  from  the  precipitated  salt,  unlike  in 
the  case  of  citric  acid,  gave  but  slight  indication  of  the  presence  of 
lead,  not  the  heavy  precipitates  as  found  in  the  case  of  the  citrate. 
This  would  indicate  that  tartrate  of  lead  is  but  slightly  soluble 
in  water,  considerably  less  so  than  the  corresponding  citrate. 
This  is  confirmed  by  an  examination  of  the  precipitated  salt. 
PRECIPITATED  SALT. 
According  to  the  above-cited  authority  the  monoplumbic  salt, 
prepared  by  the  precipitation  of  a  soluble  lead  salt  by  means  of  tar- 
