AmjIn^8P77?rm'}         Ammonio-Cupric  Sulphate.  13 
showing  an  oxalate.  This  with  the  brown  resin  indicates  that  eugenic 
acid  (C10H12O2)  was  present. 
When  the  nitric  acid  was  added,  an  odor  so  familiar  was  produced 
that  it  took  some  time  to  place  it.  It  was  that  of  aromatic  vinegar, 
indicating  that  acetic  acid  was  also  among  the  products  of  the  decom- 
position of  residue  left  in  the  test  tube. 
SOLUTION  OF    AMMONIO-CUPRIC   SULPHATE   AS  A 
TEST  FOR  GRAPE-SUGAR. 
By  Fred.  B.  Power. 
In  some  experiments  with  grape-sugar,  the  action  of  a  very  dilute 
solution  of  ammonio-cupric  sulphate  was  observed  ;  this  reaction  being 
of  some  interest,  and,  to  my  knowledge  not  having  been  previously 
announced,  the  following  observations  may  be  noted  : 
If  a  drop  of  the  ordinary  test  solution  of  cupric  sulphate  (one  part 
of  the  salt  in  fourteen  parts  of  water)  be  allowed  to  fall  into  a  test 
tube,  a  slight  excess  of  ammonia  water  above  that  required  for  the 
resolution  of  the  precipitate,  added,  and  further  diluted  with  a  small 
quantity  of  water,  by  the  addition  of  a  few  drops  of  a  solution  of  grape- 
sugar,  and  heating  over  a  gas  flame  to  the  boiling  point,  the  liquid  be- 
comes perfectly  decolorized  in  a  few  seconds.  It  was  found  that  a  solu- 
tion containing  one  drop  of  a  solution  of  cupric  sulphate  of  the  above 
strength,  which  forms  a  deeply  tinted-blue  liquid  upon  the  addition  of 
an  excess  of  ammonia  water,  becomes  perfectly  colorless  in  transmitted 
and  reflected  light  by  heating  with  four  drops  of  a  solution  of  one  gram 
of  grape-sugar  in  100  cubic  centimetres  of  water;  this  degree  of  dilu- 
tion of  the  saccharine  solution  seems  to  approach  the  minimum  for  the 
attainment  of  a  marked  result  in  the  use  of  this  test,  and  corresponds 
approximately  to  the  detection  of  0*005  gram  or  y'g  grain  of  crystal- 
line grape-sugar. 
The  decolorized  solution  after  standing  for  a  few  hours  exposed  to 
the  air  again  assumes  its  original  blue  color. 
Milk-sugar  and  dextrin  produce  the  same  reaction  as  grape-sugar, 
although  a  somewhat  more  concentrated  solution  of  dextrin  is  required. 
Pure  mannit,  which  has  no  reducing  effect  upon  the  solutions  of 
Trommer  and  Fehling,  has  also  no  effect  upon  the  ammonio-cupric 
solution. 
