584 
Rubus  Villosus. 
f  Am.  Jour.  Pharm. 
\   December,  1894. 
TANNIN  OF  RUBUS  VILLOSUS. 
Estimation. — That  a  knowledge  might  be  gained  of  the  relative 
value  of  the  bark  sold  in  the  market  and  that  freshly  gathered,  the 
writer  made  collections  of  the  drug  in  the  vicinity  of  Philadelphia, 
on  November  24,  1892,  January  2,  1893,  ancI  February  2,  1893. 
The  three  samples  which  he  obtained  were  numbered,  respectively, 
three,  four  and  five,  were  taken  from  medium-sized  roots,  and  were 
carefully  deprived  of  earth  and  of  the  woody  portion  which  is  fre- 
quently found  in  commercial  bark.  Samples  one  and  two  were 
representative  of  the  market  article. 
The  tannin  was  estimated  by  the  gelatin  and  alum  method. 
Somewhat  higher  results  were  obtained  from  samples  three  and 
four  by  the  "  hide  "  process. 
For  comparison,  the  tannin,  moisture  and  ash  of  the  fresh  bark, 
and  also  the  amount  of  tannin  in  the  thoroughly  dried  drug,  are 
given  in  the  subjoined  table  in  percentages  : 
Sample. 
Ash. 
Moisture. 
Tannin  in 
moist  drug. 
Tannin  in 
absolutely 
dry  drug. 
I 
3-68 
9-86 
I3*46 
I4'93 
II 
4*53 
878 
10*84 
11-89 
III 
4-56 
45*15 
10-37 
18-91 
IV 
3-87 
38-44 
1072 
17-42 
V 
4*3i 
9*22 
1274 
14-03 
Preparation  and  Purification. — Twelve  hundred  grams  of  sample 
No.  II  were  macerated  with  water  for  twenty-four  hours,  and  then 
percolated  with  the  same  solvent  until  six  litres  of  liquid  were 
obtained. 
Several  methods  for  the  separation  and  purification  of  the  tannin 
of  the  percolate  were  then  tried. 
A  portion  of  the  liquid  was  agitated  with  acetic  ether,  but  this 
solvent  removed  only  a  small  amount  of  a  yellowish  substance.  The 
entire  percolate  was  then  completely  precipitated  with  lead  acetate. 
The  precipitate  was  collected  on  a  filter,  allowed  to  drain,  and 
was  then  decomposed  by  hydrogen  sulphide.  The  lead  sulphide 
was  separated  ;  the  liquid  boiled  to  remove  hydrogen  sulphide,  and 
then  filtered. 
One-sixth  of  this  filtrate,  representing  one  litre  of  the  original 
