Tests. — The  pentoses  give  the  phloroglucin  reaction  (as  do  also
lactose  and  galactose),  but  with  pentose  the  color  test  is  confirmed  by
its  characteristic  spectrum,  which  is  also  true  of  glycuronic  acid,  which
gives  exactly  the  same  test.  This  test,  according  to  Tollen,  is  as  fol-
lows :  To  a  few  cubic  centimetres  of  urine  are  added  an  equal  part  of
HCl  (sp.  gr.  1. 19),  then  from  25  to  30  mg.  of  phloroglucin,  and  the
solution  warmed  until  a  red  color  appears.  This  solution  is  examined
spectroscopically  at  once  for  a  band  in  the  green.  If  not  present,  the
solution  is  brought  to  a  boil  and  the  spectrum  again  tested.
Salkowski  recommends  the  following  modification:  Fiv^e  to  six
cc.  of  fuming  HCl  are  warmed  and  saturated  with  phloroglucin,  leav-
ing some  undissolved.  This  solution  is  then  halved.  To  the  one  test-
tube  is  added  0.5  cc.  of  the  suspected  urine,  and  to  the  other  0.5  cc
of  normal  urine.  Both  test-tubes  are  then  placed  in  a  beaker  of  boiling
water.  If  pentose  be  present,  this  tube  will  soon  present  a  red  color,
which  begins  above  and  extends  downward.  The  solution  is  exam-
"  Verb.  d.  XIX.  Kongr.  f.  inn.  Med.
THE  UEINE  181

ined  spectroscopically.  The  test-tubes  should  be  removed  from  the
water-bath  as  soon  as  the  red  begins  to  appear.
