Amjm^'i?fearm'}  Sugar  in  Urine.  295 
solution  remaining  after  the  reduction  with  urine,  reacts  with  the 
phenylhydrazine  liberating  the  nitrogen. 
In  theory,  and  then  only  with  pure  solutions,  this  method  for  the 
estimation  of  sugar  is  good;  but  I  do  not  consider  the  method  of  any 
great  utility  with  urine,  basing  my  opinion  entirely  on  theoretical 
grounds  and  experiments  carried  on  with  Fehling's  solution  itself. 
In  handling  a  solution  as  complex  as  the  urine,  we  must  not  forget 
that  there  are  a  number  of  compounds  present,  or  might  be  present, 
which  have  more  or  less  of  a  reducing  action  on  Fehling's  solution. 
Bodies  of  this  character  are  uric  acid,  creatinine,  allantoin,  nucleoal- 
bumin,  lactic  acid  and  biliary  coloring  matters,  consequently,  all 
probable  constituents  of  urine.  These  compounds,  however,  are 
usually  present  in  such  small  quantities  that  their  presence  becomes 
of  especial  importance  where  the  percentage  of  sugar  is  small,  and 
just  in  a  case  of  this  kind  it  is  of  the  utmost  importance  to  have  a 
method  which  can  be  used  in  all  cases  without  fearing  that  by  the 
action  of  the  reagent  on  other  constituents  of  the  urine  a  similar 
reaction  might  be  brought  about.  This,  to  my  mind,  is  the  most 
serious  objection  to  this  method — in  fact,  to  all  the  methods  using 
the  copper  salts. 
In  my  laboratory  practice  I  have  repeatedly  proven  to  my  own 
mind  the  statement  just  made  in  reference  to  Fehling's  solution.  I 
recall  one  case  especially.  The  urine  was  furnished  me  with  the 
statement  that  it  showed  Fehling's  reaction  rather  strongly.  It  was 
from  a  lady  looking  forward  to  an  early  confinement,  and  a  careful 
examination,  with  the  elimination  of  all  possible  errors,  was  abso- 
lutely necessary.  I  found  that  the  Fehling's  test  and  the  Boett- 
ger's  test  were  both  strongly  reduced;  but  on  subjecting  the  urine  to 
the  action  of  yeast,  no  fermentation  took  place  and  no  difference  in 
specific  gravity,  as  by  the  Roberts  method,  was  observed.  Making 
examinations  daily,  I  found  that  in  about  three  or  four  days  this  appar- 
ent sugar  reaction  had  entirely  disappeared.  This  lady  had  been  suf- 
fering from  headache  and  had  used  one  of  the  many  headache  remedies 
found  in  the  market  at  the  present  time.  This  "  sugar"  reaction 
was  very  likely  caused  by  one  of  the  conjugate  glycuronic  acids. 
At  the  present  time  I  do  not  depend  entirely  on  Fehling's  test  or 
Boettger's  test,  but  run  through  the  principal  chemical  tests,  and  in 
cases  of  uncertainty  I  use  the  Roberts  differential  specific  gravity 
method  for  the  quantitative  estimation  of  glucose. 
