606  Analysis  of  Blackberry  Bark  {AmB™*\marm' 
The  alcoholic  percolate  of  the  drug  was  macerated  with  freshly 
precipitated  ferric  hydrate  ;  the  latter,  prepared  from  500  cc.  of  solu- 
tion of  tersulphate  of  iron,  is  used  for  the  tincture  from  500  gm.  of  bark. 
The  alcoholic  filtrate,  to  which  the  washings  have  been  added,  is  sub- 
jected to  distillation  until  the  alcohol  has  been  completely  removed; 
the  cloudy  residue  is  filtered  and  the  filtrate,  mixed  with  absolute  ether 
and  frequently  shaken,  is  set  aside  for  twelve  hours,  when  the  gluco- 
side  is  separated  in  fine  needles.  A  more  complete  precipitation  takes 
place  when  chloroform  is  used  instead  of  ether ;  but  the  precipitate  is 
amorphous. 
Nearly  as  good  results  are  obtained  by  mixing  the  powdered  drug 
with  milk  of  lime,  drying  the  mixture,  exhausting  it  with  boiling 
alcohol,  evaporating,  treating  the  residue  with  ether  and  subsequently 
dissolving  in  alcohol. 
The  glucoside,  for  which  the  name  of  villosin  is  proposed,  forms 
fine  silky  needles  melting  at  173-175°  C.  to  a  brown  mass  ;  heated 
on  platinum  foil  it  melts  and  burns  with  a  sooty  flame,  leaving  no 
residue.  It  is  freely  soluble  in  methyl,  ethyl  and  amyl  alcohols, 
sparingly  soluble  in  water,  slightly  soluble  in  petroleum  benzin, 
insoluble  in  chloroform  and  nearly  so  in  ether.  The  taste  is  bitter, 
best  perceptible  in  the  alcoholic  solution.  The  aqueous  solution  is  not 
precipitated  by  lead  acetate,  but  yields  a  precipitate  with  lead  sub- 
acetate.  Villosin  does  not  reduce  silver  nitrate,  even  on  heating.  Fer- 
rous and  ferric  salts  cause  no  change.  Alkalies  color  lemon  yellow. 
Sulphuric  acid  colors  light  brown,  changing  to  deep  violet  with  little 
water.  Sulphuric  with  a  drop  of  nitric  acid  colors  deep  orange,  then 
red,  by  heat  destroyed.  Froehde's  reagent  colors  dark  brown,  and  on 
heating,  brown  green ;  but  Froehde's  reagent  with  a  drop  of  nitric 
acid  gives  a  red  color.  An  aqueous  solution,  containing  in  5  cc. 
0'030  gm.  of  the  glucoside,  yielded  with  Fehling's  solution  0*020 
gm.  precipitate  ;  on  boiling  the  solution  previously  with  dilute  acid 
the  precipitate  weighed  0'024  gm. 
For  estimating  the  tannin  10  gm.  of  the  bark  were  exhausted  with 
93  per  cent,  alcohol,  the  tincture  evaporated,  and  the  extract  dissolved 
in  water.  Using  Mueller's  method  9*19  per  cent,  of  tannin  were 
found ;  by  Guenther's  method,  9*88  per  cent.,  and  by  LoewenthaPs 
method  10'3  and  10*4  per  cent.  But  working  with  cold  infusions  of 
the  bark,  the  results  were  as  follows  :  by  Guenther's  method  10*0 
per  cent.,  and  by  Loewenthal's  method  ll'l,  12*5  and  11*8  per  cent. 
