364  Some  Recent  Sugar  Reactions.  {Am'^;^tm' 
The  delicacy  of  the  reaction  may  be  placed  between  o-i  percent, 
and  0-125  per  cent,  of  glucose. 
Milk  sugar  reacts  in  the  same  manner  as  glucose,  but  the  point 
of  delicacy  must  be  placed  at  a  higher  percentage  point. 
Reaction  upon  Glycuronic  Urines. — An  investigation  was  also 
made  to  determine  the  effect  of  urine  passed  after  the  administra- 
tion of  certain  drugs  upon  this  test. 
Some  specimens,  such  as  creosote  and  salicylate  urine,  will,  on 
boiling,  assume  a  brown-black  color,  which,  on  dilution  with  water, 
show  an  almost  complete  absence  of  green. 
The  precipitate  is,  in  such  cases,  gray  or  black. 
It  has,  however,  been  observed  by  the  writer  that  a  subsequent 
addition  of  -5  per  cent,  to  1  per  cent,  of  glucose  to  such  urine  will 
give  no  evidence  of  reduction,  the  dark  mixture  obscuring  the  phys- 
ical evidences. 
A  specimen  of  creasote  urine,  to  which  an  addition  of  0-5  per 
cent  of  glucose  was  made,  gave,  on  boiling  with  an  equal  volume  of 
the  test  liquid,  a  gray- black  precipitate  with  a  red-brown  super- 
natant liquid.  Comparison  with  the  sugar-free  sample,  treated  in  a 
similar  manner,  showed  no  material  physical  variations. 
The  precipitation  of  Cu20  in  the  saccharine  sample  was  com- 
pletely obscured. 
Worm-Mueller' s  Modification  of  Fehling's  Test. — The  researches 
of  several  investigators  have  led  to  the  determination  of  the  various 
temperature  points,  at  which  the  reduction  of  Fehling's  solution 
takes  place,  when  acted  upon  by  other  reducing  urine  constituents 
besides  glucose.  Those  of  primary  importance  are  uric  acid  and 
creatinine. 
Glucose  reduces  Fehling's  solution  at  a  temperature  of  from  6o° 
to  700  C,  the  same  being  approximately  the  case  also  with  milk 
sugar. 
The  reduction  produced  by  uric  acid  is  at  this  point  feeble,  the 
same  taking  place  only  at  a  temperature  close  to  the  boiling 
point. 
In  the  case  of  creatinine,  slight  reduction  is  stated  to  take  place 
between  60  0  and  70  0  C,  but  only  completely  between  900  and 
100°  C. 
In  normal  urine  its  reducing  power  is,  however,  regarded  as 
being  insignificant. 
