322  Arhutin  the  Bitter  Principle  of  Coivberry.  {^'^-/.^Y'lssT'^' 
under  evolution  of  red  fumes,  forming  a  reddisli  yellow  solution, 
which  after  dilution  with  water  is  yellow. 
5.  The  solutions  of  both  in  water  are  not  precipitated  by  an  alka- 
line copper  solution,  platinum  chloride,  corrosive  sublimate,  acetate 
and  basic  acetate  of  lead,  a  solution  of  iodine  in  potassium  iodide, 
tannic  and  gallic  acids. 
6.  A  very  dilute  solution  of  ferric  chloride  colors  both  blue;  they 
give  then  with  water  a  blue  solution. 
7.  A  solution  of  phosphomolybdic  acid  and  ammonia  added  to 
their  solutions  produces  an  intensely  blue  colored  liquid,  whicli  after 
some  time  turns  greenish,  and  after  a  longer  time  the  color  disappears 
entirely. 
8.  Tlie  solutions  of  both  boiled  for  some  time  with  very  dilute  sul- 
phuric acid,  then  made  alkaline  by  potassium  hydrate  and  heated  with 
an  alkaline  copper  solution,  furnish  a  deposit  of  copper  protoxide  (by 
the  glucose  formed). 
When  preparing  arbutin,  it  is,  as  I  have  found,  of  value  to  see  that 
the  liquid  containing  it  when  evaporated  has  no  acid  reaction;  the  acid 
in  it  may  be  sulphuric,  hydrochloric,  citric  or  acetic  acid,  because  they 
decompose  the  same,  as  experiments  made  (see  below  sub  1  and  2) 
will  prove.  In  order  to  avoid  this  decomposition,  and  to  collect  the 
whole  amount  of  the  arbutin  present,  it  is  necessary,  after  having  pre- 
cipitated the  decoction  of  the  leaves  by  basic  acetate  of  lead,  and  the 
filtrate  by  sulphuretted  hydrogen,  to  neutralize  the  free  acetic  acid  by 
calcium  or  magnesium  carbonate. 
1.  0*2  gram  of  pure  arbutin,  dissolved  in  20  cubic  centimeters  of 
diluted  (5  per  cent.)  acetic  acid,  gave,  after  15  minutes^  boiling  in  a 
flask  (meanwhile  restoring  from  time  to  time  the  evaporated  water) 
with  an  alkaline  copper  solution,  a  plainly  visible  reaction  of  glucose; 
after  J  hour's  boiling  the  amount  of  glucose  had  increased  consider- 
ably. " 
2.  0"2  gram  of  pure  arbutin  boiled  in  the  same  manner  with  20 
cubic  centimeters  of  Avater,  containing  3  per  cent,  of  citric  acid,  gave 
a  fair  reaction  of  glucose  after  a  lapse  of  10  minutes  already. 
Before  closing  this  article  I  will  mention  that  the  fruit  of  the  Amer- 
ican cranberry,  of  which  enormous  quantities  arebrought  into  the  mar- 
ket, has  besides  an  acid  a  decidedly  bitter  taste.  A  small  quantity  of 
the  berries  w^as  crushed  under  addition  of  water  and  an  excess  of  quick 
lime,  the  mixture  pressed,  and  the  liquid  filtered.    The  filtrate  gave 
