148      EXAMINATION  OF  DEPOSIT  FROM  TINCTURA  RHEI. 
EXAMINATION  OF  THE  DEPOSIT  FROM  TINCTURA 
RHEI,  U.S.  P. 
By  James  T.  King. 
The  yellow  deposit  in  a  storage  bottle  of  tincture  of  rhubarb, 
U.S. P.,  was  collected  on  a  filter,  washed,  and  dried  until  it 
ceased  to  lose  weight. 
Ten  grains  of  this  was  treated  with  liquor  potassse  until  no 
more  would  dissolve  ;  it  was  then  filtered,  washed  and  dried. 
The  portion  insoluble  in  potassa  consisted  principally  of  ex- 
tractive. 
The  filtrate  was  supersaturated  with  hydrochloric  acid  and 
filtered ;  the  precipitate,  well  washed  and  dried,  weighed  8  grs. 
This  was  treated  with  chloroform,  and  the  solution  allowed  to 
evaporate  spontaneously  ;  when  well  dried,  was  weighed,  giving 
5*4  grs.  of  nearly  pure  chrysophanic  acid.  The  2*6  grs.  insolu- 
ble in  chloroform  were  destitute  of  any  taste  of  rhubarb,  soluble 
in  alcohol ;  on  platinum  foil  with  heat  it  fused,  then  ignited, 
giving  off"  a  yellow  flame,  leaving  no  ash  or  residue.  It  is  pro- 
bably resin.  Finding  in  the  deposit  so  large  a  per  cent,  of 
chrysophanic  acid,  which  is  supposed  to  be  one  of  the  more  act- 
ive principles  of  rhubarb,  the  following  experiment  was  made  to 
determine  what  portion  of  the  soluble  matter  of  rhubarb  would 
be  precipitated  in  a  given  time. 
One  pint  of  the  tincture  of  rhubarb  was  made  according  to  the 
U.  S.  P.  The  materials  weighed  840  grs.  When  the  tincture 
was  finished,  the  drug  appeared  to  be  exhausted  of  all  matter 
soluble  in  the  menstruum.  The  undissolved  portion  was  dried 
on  a  water-bath,  and  weighed  443  grs.,  showing  a  loss  of  397 
grs.  By  previous  examination  the  rhubarb  was  found  to  lose  10 
per  cent,  of  moisture  ;  this  would  leave  313  grs.  of  matter  in 
solution. 
The  tincture  was  placed  on  a  shelf  in  the  store  room  exposed 
to  the  difi'used  light,  and  occasionally  opened.  At  the  expira- 
tion  of  eight  months  it  was  filtered,  the  precipitate  washed  and 
dried.  It  weighed  only  3*1  grs., — about  one  per  cent.  This 
was  treated  with  potassa  and  hydrochloric  acid  in  the  same  man- 
ner as  the  other  precipitate  or  deposit,  and  gave  1*2  grs.  chryso- 
