484  Aqueous  Iluid  Extract  of  Rhubarb.  {^N^wi™ 
phseoretin,  chrysophanic  acid  and  erythroretin  were  tried,  to  be  pre- 
pared by  the  directions  of  Schlossberger  and  Dopping,  as  detailed  in 
W.  and  B.  Dispensatory  of  1858,  page  647. 
The  alcoholic  percolate  was  evaporated,  by  means  of  a  water-bath, 
to  dryness ;  this  dry  extract  (a),  moistened  with  a  little  water,  waa 
introduced  into  a  properly  prepared  funnel  and  exhausted  with  water. 
This  aqueous  percolate  was  evaporated  to  dryness  by  means  of  a 
water-bath,  dissolved  in  a  small  quantity  of  alcohol,  and  treated  with 
ether  (b).  A  precipitate  (c)  was  produced,  which  was  separated  by 
filtration  and  treated  with  alcohol,  which  dissolved  only  part  of  the 
precipitate.  This  alcoholic  solution  was  again  carefully  evaporated 
to  dryness,  and  was  found  to  possess  all  the  properties  of  phseoretin, 
behaving  like  it  to  water,  alcohol,  ether,  water  of  ammonia,  and  giv- 
ing an  orange-yellow  precipitate  by  supersaturating  the  ammoniacal 
solution  with  muriatic  acid.  The  residue  of  the  precipitate  (<?),  which 
is  insoluble  in  alcohol  (probably  aporetin),  was  partly  soluble  in  water. 
The  ethereal  solution  (b),  from  which  the  precipitate  had  been  ob- 
tained, was  allowed  to  evaporate  spontaneously,  when  it  deposited 
small  crystals  of  a  beautiful  yellow  color,  which  were  collected  on  a 
filter.  They  yielded  with  water  of  ammonia  a  beautiful  carmine  so- 
lution ;  with  nitric  acid,  slightly  heated,  a  dark  red  color,  and  on  the 
addition  of  water  of  ammonia  a  violet  color.  The  crystals  dissolve 
with  a  yellow  color  in  ether.  The  carmine-colored  solution  of  these 
crystals  with  carbonate  of  potassa  solution  when  evaporated  changes 
first  to  violet  and  then  to  blue.  All  these  reactions  show  without 
doubt  that  the  crystals  are  crysophanic  acid. 
The  ethereal  solution  (6),  after  it  had  ceased  to  deposit  crystals, 
was  evaporated,  by  means  of  a  water-bath,  to  dryness,  whereby  a  red- 
dish-brown resin  (d),  probably  erythroretin,  was  obtained,  for  which 
no  particular  reactions  have  been  given. 
The  residue  from  the  alcoholic  extract  (a)  was  treated  in  the  fol- 
lowing manner :  It  was  dried  in  an  evaporating  dish,  mixed  with  al- 
cohol to  a  pasty  consistence,  and  in  a  funnel  exhausted  with  alcohol  (e). 
A  considerable  portion  of  this  residue  remained  undissolved,  which 
was  exhausted  with  cold  ether  (/),  then  treated  in  a  flask  with  hot 
ether,  and  the  insoluble  portion  separated  by  filtration.  This  insolu- 
ble portion  was  found  to  be  not  quite  soluble  in  hot  alcohol,  but  en- 
tirely so  in  water  of  ammonia  with  the  aid  of  a  gentle  heat ;  the 
solution  was  of  a  dark  brown  color. 
