AmjJ?yir'I879*rm  }  Lactucarium  from  Lactuca  Canadensis.  345 
deprived  of  some  of  their  bitterness.  Ammonia  will  not  precipitate  it, 
but  rather  tends  to  alter  the  taste.  It  is,  however,  precipitated  from 
alcohol  by  water,  and  may  thus  be  purified  by  repeated  precipitation 
and  crystallization.  Nitric  acid  will  not  dissolve  it,  nor  will  the  addi- 
tion of  alcohol  facilitate  this  end.  The  characteristics  given  by 
Kromayer,  Ludwig  and  Walz  are  in  accordance  with  these  results. 
Lactucic  acid  is  precipitated  by  basic  acetate  of  lead,  care  being 
taken  that  an  excess  is  not  used,  for  it  is  soluble  in  that  salt  when  in 
excess.  It  changes  blue  litmus  paper  to  red,  proving  its  acidity  ;  has 
an  acrid,  bitter  taste  ;  is  soluble  in  alcohol,  both  hot  and  cold,  insoluble 
in  petroleum  benzin,  bisulphide  of  carbon,  ether  and  chloroform,  and 
has  a  brownish-green  color. 
Lactucopicrin  is  a  brown  amorphous  mass,  and  may  be  purified  by 
repeated  treatment  with  ether,  chloroform  or  alcohol,  filtering  and 
evaporating.  It  has  a  strong  and  purely  bitter  taste,  is  soluble  in  alco- 
hol, chloroform,  ether  and  water,  and  is  not  precipitated  by  lead  salts 
from  its  solution. 
The  residue  of  the  lactucarium,  left  after  the  above  principles  had  been 
removed  by  hot  alcohol,  was  treated  with  bisulphide  of  carbon,  which 
dissolved  a  large  amount  of  caoutchouc  (gum  elastic),  but  there  yet 
remained  a  residue,  which  was  treated  with  ether,  removing  a  pale- 
yellowish  granular  powder  ;  with  chloroform,  removing  the  remaining 
caoutchouc  and  some  of  the  coloring  matter,  and  with  alcohol,  which 
yielded,  on  evaporation,  a  brownish,  bitter,  amorphous  mass  resembling 
lactucopicrin.  Water  extracted  a  large  amount  of  coloring  matter. 
The  residue  which  was  now  left  defied  the  solvent  powers  of  carbon- 
disulphide,  ether,  chloroform,  alcohol,  water  and  acetic  acid. 
The  yellowish  powder  obtained  on  the  evaporation  of  ether  in  the 
above  treatment  closely  resembles  lactucerin,  but  the  identity  of  the 
two  was  not  proven.  When  heated  it  will  melt,  and  volatilize  if  the 
temperature  is  increased.  On  cooling  it  forms  a  resinous  mass.  It  is 
soluble  in  hot  alcohol,  petroleum  benzin  and  chloroform  ;  insoluble  in  hot 
or  cold  water.  Sulphuric  acid  dissolves  it,  but  does  not  char  it.  Nitric 
acid  has  little  or  no  effect.  Muriatic  acid  dissolves  it  slightly.  Acetic 
acid  and  ammonia  have  no  effect.  It  is  precipitated  from  the  alcoholic 
solution  by  water. 
1  he  statement  of  Aubergier  regarding  the  worthlessness  of  this 
plant  is  undoubtedly  wrong,  as  there  exist,  beyond  question,  several 
