Am.  Jour.  Pharm.  \ 
July,  1896.  J 
Some  Recent  Sugar  Reactions. 
363 
The  fact  that  the  end  reaction,  by  the  discharge  of  the  blue  color, 
can  be  readily  observed  forms  one  of  the  great  advantages  of  Feh- 
ling's  solution  over  the  safranine  test  in  quantitative  estimations. 
The  Cupric  Salicylate  Test. — A  number  of  modifications  of  the 
copper  test  have  been  proposed,  the  most  recent  of  which  is  the 
following  solution  : 
Parts. 
Cupric  sulphate    .  .  2 
Sodium  salicylate  cryst  2 
Sodium  carbonate  8 
Distilled  water,  a  sufficient  quantity  to  make  ico  parts. 
The  filtered  solution  has  a  dark  green  color,  and  the  reducible 
constituent  is  stated  to  be  cupric  salicylate. 
On  boiling  the  liquid  in  a  test  tube,  the  precipitate  formed  is  from 
gray  to  black,  coating  the  sides  of  the  tube. 
If  to  5  c.c.  of  this  solution  a  few  drops  of  diabetic  urine  are 
added  and  boiled,  the  precipitate  will  be  dirty  green. 
On  the  further  addition  of  urine,  the  precipitate  will  be  of  a  yel- 
low color. 
The  following  directions  are' given: 
Equal  parts  of  the  copper  test  liquid  and  urine  are  heated 
together  to  the  boiling  point,  until  a  precipitate  is  formed. 
If  the  same  is  gray  or  black,  no  sugar  is  present. 
The  writer  subjected  this  test  to  a  number  of  examinations,  with 
a  view  of  determining  its  delicacy,  as  well  as  its  action  upon  certain 
glycuronic  urines. 
A  number  of  specimens  of  normal  urine,  examined  as  directed, 
gave  precipitates  which  varied  in  the  shade  of  green. 
The  important  point  in  this  reaction  seems  to  be  in  the  appear- 
ance of  a  yellowish  or  yellowish-green  tint  in  the  liquid  overlying 
the  precipitate  in  the  case  of  diabetic  urine. 
Urine  containing  -25  per  cent,  of  glucose  will,  if  the  proportions 
of  urine  and  test  liquid  are  as  directed  above,  show  a  complete  re- 
duction by  prolonged  boiling. 
Urine  containing  -125  per  cent,  of  glucose  will  not  completely 
reduce,  but  gives  a  yellowish-green  supernatant  liquid. 
Samples  containing  -063  (J-g-)  per  cent,  will  not  reduce  the  solu- 
tion, and  the  color  of  the  supernatant  liquid  will  but  slightly  differ 
from  that  produced  with  perfectly  normal  urine. 
