552 
Varieties. 
(  A.m.  Jour.  Pharm. 
1      Nov.,  1878. 
taneously.  On  treating  the  semi-crystalline  residue  with  hot  alcohol,  and,  after  the 
solution  had  cooled  somewhat,  pouring  off  from  resin  which  was  deposited,  crystals 
separated  which  were  purified  by  crystallization  from  acetone. 
From  his  own  analyses  and  those  of  Rose,  Dragendorff,  etc.,  the  author  deduces 
the  formula,  C15H2iO,  for  euphorbone.  This  substance  is  isomeric  with  lactucone ; 
or  perhaps  it  may  possess  the  double  formula,  C30H48O2,  and  so  be  an  isomeride  of 
echicerin.  Euphorbone  melts  at  113  —  ii4°C.  For  a  chloroform  solution  the 
rotatory  power  of  euphorbone  is  (a)d=-f  i8'8  at  15°;  and  for  an  ethereal  solution 
(«)d— -f- 1 1'7°. — Ibid.,  October,  1878,  from  Liebigs  Annalen,  cxcii,  193 — 195. 
Tannin  and  Bitter  Principle  of  Hops.  By  C.  Etti. — The  substance  named 
"  lupulo  tannic  acid  "  by  the  authoi  does  not  pi ecipitate  gelatin  ;  if,  however,  it  is 
dried  at  120 — 1300,  it  changes  from  yellowish-white  to  red,  loses  water,  and  when 
dissolved  in  very  dilute  alcohol,  precipitates  gelatin  completely  just  like  ordinary 
tannin. 
On  heating  the  yellowish  alcoholic  solution  of  the  original  tannin  on  the  water- 
bath,  it  becomes  red,  and  on  evaporation  a  dark  red  residue  remains,  which  also 
precipitates  gelatin  when  again  dissolved  in  dilute  alcohol.  The  author  calls  this 
"  phlobaphen. 11 
Analysis  gives  the  same  composition  for  this  as  for  the  red  compound  obtained 
by  heating  the  lupulo-tannic  acid  at  120  — 1300,  each  having  the  formula  C50H46O25 ; 
and  they  may  be  supposed  to  result  from  the  expulsion  of  a  molecule  of  water  from 
two  molecules  of  tannic  acid  of  the  formula  C„- H.,,01fi. 
zo      l\  lb 
The  coarselv  powdered  hop  flowers  are  placed  in  an  extraction  apparatus,  and 
after  being  freed  from  resin  and  bitter  principle  as  much  as  possible,  the  mass  is 
extracted  with  20  per  cent  alcohol.  On  evaporating  to  a  small  bulk  and  cooling, 
a  red  precipitate  of  phlobaphen  is  formed  5  this  is  dissolved  in  90  per  cent,  alcohol, 
evaporated  to  dryness  and  heated  to  120 — 1300.  If  it  tastes  bitter,  the  bitter  prin- 
ciple may  be  removed  by  ether.  Phlobaphen  is  easily  soluble  in  alkalis,  and  is  pre- 
cipitated unchanged  by  dilute  mineral  acids  On  boiling  the  freshly  precipitated 
and  not  previously  heated  phlobaphen  with  dilute  mineral  acids  it  is  decomposed, 
glucose  and  one  molecule  of  water  being  split  off. 
As  the  phlobaphen  is  easily  prepared,  is  constant  in  composition,  and  precipitates 
gelatin  solution  completely,  it  may  be  estimated  quantitatively  like  tannin,  and  may 
be  used  in  standardizing  the  solution  employed. 
An  etherial  extract  of  hop  flowers  contains,  besides  an  essential  oil,  chlorophyll, 
a  crystallized  white  and  an  amorphous  brown  resin,  to  which  the  bitter  principle 
adheres.  After  driving  oft'  the  ether,  90  per  cent,  alcohol  dissolves  brown  resin  and 
the  bitter  principle,  which  may  be  separated  from  each  other  by  adding  water  as 
long  as  the  resin  continues  to  be  precipitated.  Repeated  solution  in  alcohol  and 
dilution  with  water  frees  the  resin  from  the  bitter  principle.  The  aqueous  solution 
is  evaporated  in  a  vacuum  over  sulphuric  acid,  the  amorphous  residue  dissolved  in 
90  per  cent  alcohol,  again  evaporated,  and  so  on  repeatedly,  until  well-formed 
extremely  bitter,  colorless  crystals  are  obtained.  The  crystals  are  completely  solu- 
ble in  water.  These  experiments  oppose  the  idea  that  the  "  bitter  resin  "  of  hops 
can  be  dissolved  in  water  only  with  the  aid  of  sugar,  tannic  acid,  gum,  etherial  oil, 
etc.  The  brown  amorphous  resin  and  the  bitter  principle  of  hops  are  two  funda- 
mentally different  substances. — Jour.  Chem.  Soc.  [Lond.],  Oct.,  1878,  from  Dingl. 
Polyt.  J.,  ccxxviii,  354—357- 
