134 
New  Crystalline  Acid  in  Urine. 
(Am.  Jour.  Pharm. 
\      March,  1887. 
The  urine  was  treated  with  half  its  volume  of  plumbic  tribasic 
acetate  solution,  and  the  resulting  voluminous  precipitate  collected  on 
a  filter  and  washed  several  times  with  a  mixture  of  equal  parts  of  al- 
cohol and  water.  The  precipitate  was  then*  suspended  in  warm  water 
and  hydrogen  sulphide  passed  through  until  all  the  lead  was  precipi- 
tated. After  expelling  the  hydrogen  sulphide  from  the  filtrate  by 
boiling,  excess  of  plumbic  carbonate  was  added,  and  the  liquid  was 
gently  boiled  several  minutes,  and  then  filtered  while  hot.  The  fil- 
trate was  concentrated  on  the  water  bath  and  then  kept  in  a  cool  place 
to  allow  crystallization  to  occur.  The  crystals  of  the  lead  salt  which 
separated  were  washed  by  decantation  with  a  mixture  of  equal  parts 
of  alcohol  and  water  and  recrystallized  from  hot  water.  Finally, 
when  sufficiently  pure  they  were  dissolved  in  hot  water  and  the  lead 
precipitated  by  hydrogen  sulphide,  filtered,  and  the  filtrate  containing 
the  free  acid  evaporated  to  dryness  at  about  70°  C.  The  residue  was 
extracted  with  ethyl  ether,  and  the  latter  evaporated  spontaneously. 
Several  recrystallizations  from  ether,  the  final  one  from  a  mixture  of 
ether  and  water,  are  necessary  to  obtain  the  acid  in  a  fairly  pure  condi- 
tion. The  crystal  mass  was  pressed  between  bibulous  paper  and  again 
recrystallized  from  water. 
The  acid  thus  obtained  crystallizes  in  opaque  white  tetragonal  prisms, 
melts  at  140°  C,  and  sublimes  in  the  same  prismatic  form,  the  crys- 
tals generally  radiating  from  a  centre.  It  is  very  soluble  in  water  and 
in  ethyl  ether,  soluble  in  absolute  alcohol  and  also  in  ordinary  alcohol, 
sparingly  soluble  in  chloroform,  insoluble  in  benzol,  toluol,  and  in  pe- 
troleum ether. 
When  its  solution  in  ethyl  ether  is  evaporated  at  a  temperature  of 
about  60°  C,  a  slight  claret-red  tint  is  produced,  which  soon  resolves 
into  spots  of  purple.  This  purple  substance  (somewhat  resembling 
murexide)  attaches  itself  to  the  crystalline  mass,  producing  a  very 
beautiful  appearance.  The  crystals,  including  the  purple  substance, 
dissolve  in  water,  with  a  disappearance  of  the  purple  coloration.  In 
the  spontaneous  evaporation  of  the  aqueous  solution  of  the  acid  no 
change  of  color  is  noticed. 
The  acid  does  not  contain  sulphur  or  nitrogen. 
The  acid  is  absorbed  by  animal  charcoal.  When  the  urine  itself  is 
passed  through  animal  charcoal  the  filtrate  becomes  dark  claret-red  in 
color,  and  has  lost  its  reducing  property. 
Sodium  hydrate  gives  a  brownish  coloration,  beginning  at  the  sur- 
