28 
Urinary  Pigments. 
Am.  Jour.  Pharm. 
Jan.,  1888. 
URINARY  PIGMENTS.^ 
By  L.  v.  Udranszky. 
On  looking  over  the  literature  of  the  siibject  of  urinary  pigments, 
which  extends  from  the  beginning  of  the  present  century,  it  is  found 
that  the  following  conclusions  can  be  clraAvn  from  the  work  at  present 
done  on  the  subject: — (1.)  By  the  action  of -oxidizing  agents,  indigo- 
blue  and  other  indigo  compounds,  for  example,  indirubin,  can  be  ob- 
tained from  normal  urine.  (2.)  In  most  cases  urobilin,  which  is 
identical  with  hydrobilirubin,  is  also  present.  (3.)  In  addition  to  the 
foregoing,  pigments  are  obtained  by  boiling  the  urine  with  mineral 
acids,  and  are  probably  derived  from  the  splitting  up  of  certain  chro- 
mogens  in  the  urine  by  these  strong  reagents:  to  one  of  these,  the 
name  uromelamin  is  given.  It  is  to  the  investigation  of  this  third 
class  of  pigments  that  the  present  research  is  mainly  directed.  A 
litre  of  normal  urine  was  heated  for  a  quarter  of  an  hour  with  5  per 
cent,  hydrochloric  acid,  and  extracted  with  amyl  alcohol ;  on  evapo- 
rating the  alcoholic  extract,  a  brownish -black,  amorphous  residue  was 
ol)taiued  w^eighing  0'68  gm.  This  is  the  ordinarily  received  method 
of  obtaining  this  pigment.  The  experiment  was  repeated,  using  dis- 
tilled water  instead  of  urine,  and  a  residue  weighing  0.51  gm.  was 
obtained,  having  the  same  characters,  including  spectroscopic  appear- 
ances. The  prolonged  action  of  hydrochloric  acid  in  the  cold  has  the 
same  action  on  amyl  alcohol.  What  this  resinous  substance  is  was  not 
fui'iher  investigated;  it  was  found,  however,  that  the  alcohol  after 
distillation  still  possessed  the  same  action  on  polarized  light  as  previous 
to  the  separation  of  the  pigment  from  it.  This  admixture  of  the 
resinous  substance  from  the  reagents  used  with  the  urinary  pigment 
could  not  be  prevented  by  attempting  to  wash  the  acid  away  from  the 
alcohol  by  the  use  of  water ;  it  was  not  found  possible  to  remove  the 
acid  in  this  way.  By  neutralizing  the  mixture  with  chalk,  however, 
the  author  considers  he  has  been  able  to  obviate  this  source  of  error. 
On  account,  however,  of  the  unsatisfactory  nature  of  amyl  alcohol  as 
a  reagent,  a  method  was  sought  for  in  which  it  was  not  necessary  to 
employ  it.  The  method  ultimately  adopted  was  as  follows : — Normal 
urine  was  evaporated  to  about  one-sixth  of  its  original  bulk  at  60°  ; 
^Zeit.  physiol.  Chem.,  xi  537 — 560.  Eeprinted  froili  Jour.  Chem.  So^.  1887., 
p.  1133. 
