206  Marrubiin  and  its  Dichlorine  Derivative.  {^l^Xm^' 
treatment  with  benzol,  but  without  success  ;  the  reason  for  this,  I 
think,  is  the  following  :  the  crystals  are  accompanied  in  the  extract, 
besides  the  coloring  and  other  foreign  matter,  by  what  seemed  to 
be  a  resinous  substance,  which  was  dissolved  along  with  them  by  the 
alcohol,  and  separated  with  them  from  its  solution,  thus  rendering  it 
difficult  for  the  bitter  principle  to  crystallize;  hot  benzol,  on  the  other 
hand  dissolved  the  crystals  and  the  resinous  substance  at  first,  but 
when  allowed  to  stand  for  twenty-four  hours,  retained  the  greater  part 
of  the  resinous  substance  in  solution,  and  deposited  the  crystals  with 
only  a  small  quantity  of  the  resinous  substance  adhering.  When 
these  impure  crystals  were  treated  with  a  fresh  portion  of  hot 
benzol,  the  marrubiin  was  dissolved,  but  the  contaminating  resin, 
for  the  most  part,  did  not  go  into  solution.  From  the  2^  kilo- 
grammes of  herb  extracted  about  20  grammes  of  purified  crystals 
were  obtained. 
These  crystals  melted  at  I54°-I55°  C,  and  on  cooling  solidified  to 
a  crystalline  mass. 
When  treated  with  strong  sulphuric  acid  a  dark  brown  color  was 
produced. 
Strong  nitric  acid  produced  a  similar  reaction. 
Strong  hydrochloric  acid  produced  no  change,  even  on  heating. 
When  Fehling's  solution  was  heated  with  a  hot-water  solution  of 
marrubiin  on  a  water-bath  for  thirty  minutes,  it  was  not  reduced. 
Fehling's  solution,  when  heated  on  a  water-bath  for  thirty  minutes 
with  a  hot-water  solution  of  marrubiin,  which  had  previously  been 
boiled  with  hydrochloric  acid,  was  not  reduced. 
The  alcoholic  solution  of  marrubiin  has  a  neutral  reaction, 
The  alcoholic  solution  of  marrubiin,  when  treated  with  alcoholic 
ferric  chloride,  was  not  changed  ;  alcoholic  lead  acetate  produced  no 
change  ;  alcoholic  tannin  solution  produced  no  change  ;  ammoniacal 
silver  nitrate  solution,  in  the  cold,  was  not  reduced  by  a  hot  aqueous 
solution  of  marrubiin ;  the  same  reagent  when  heated  in  a  water- 
bath  was  not  reduced ;  but  as  the  solution  became  more  concen- 
trated, the  marrubiin  gradually  separated  from  solution  on  the  bot- 
tom of  the  tube. 
The  alcoholic  solution,  as  well  as  the  crystals,  had  a  persistently 
bitter  taste.  On  the  addition  of  water,  the  alcoholic  solution  be- 
comes turbid  white.  Marrubiin  crystallizes  in -lustrous  needles  ar- 
ranged in  star- shaped  groups,  from  hot  alcohol  when  not  concen- 
