Am  Jour.  Pharm. 
June,  1884. 
Thapsia  Resin. 
325 
THAPSIA  RESIN. 
By  F.  Canzonem. 
The  root  of  Thapsia  Garganica,  a  plant  known  for  its  vesicating 
properties,  yields  to  boiling  alcohol  a  white  amorphous  waxy  substance, 
slightly  soluble  in  ether  and  carbon  bisulphide,  and  melting,  after 
purification,  at  90°.  This  substance,  however,  forms  but  a  small  part 
of  the  thapsia  root.  More  abundant  and  important  constituents  are 
obtained  by  treating  the  dried  and  chopped  root  in  a  percolator  with 
ether,  whereby  a  yellow  solution  is  obtained,  which,  on  distilling  off 
the  ether,  yields  an  amber-colored  syrupy  resin  possessing  strong  vesi- 
cating properties.  This  acid  dissolves  in  strong  aqueous  potash  at 
ordinary  temperatures  and  in  dilute  potash  when  heated — in  both 
cases  with  great  rise  of  temperature — and  on  neutralizing  the  resulting 
solution  with  hydrochloric  acid,  a  yellow  curdy  precipitate  is  formed, 
having  an  unpleasant  odor,  and  consisting  of  a  mixture  of  liquid  and 
solid  ethers  and  fatty  acids,  together  with  resinous  substances.  From 
this  mixture  of  products,  the  author  has  obtained:  (1.)  An  octoic  or 
caprylic  acid,  C8H1602.  (2.)  A  new  acid  of  the  series  CnH2n_204,  which 
he  designates  as  thapsic  acid.  (3.)  A  non-azotised  neutral  vesicating 
substance. 
This  last  constituent  was  obtained  in  very  small  quantity  only,  and 
in  some  preparations  was  altogether  absent ;  it  is  moreover  very  diffi- 
cult to  purify  from  resinous  substances  and  wax,  by  which  it  is  gene- 
rally accompanied.  It  dissolves  in  hot  alcohol,  and  separates  on 
cooling  in  shining  needles  melting  at  87° ;  also  in  ether  and  in  carbon 
bisulphide ;  all  its  solutions  possess  vesicating  properties.  Heated  with 
strong  potash-lye,  it  dissolves  partially  and  is  precipitated  in  the  crys- 
talline state  on  diluting  the  solution  with  water.  It  is  not  altered 
by  boiling  with  strong  acids.  Heated  on  platinum  foil,  it  burns  away 
without  residue,  emitting  a  pleasant  odor. 
Thapsic  Acid,  C16H30O4,  is  obtained  by  pressing  between  paper  the 
curdy  precipitate  formed  on  adding  hydrochloric  acid  to  the  solution 
of  the  resin  in  aqueous  potash,  and  crystallizing  it  several  times  from 
boiling  alcohol  with  addition  of  animal  charcoal.  It  forms  white 
shining  scales  melting  at  123 — 124°,  nearly  insoluble  in  water,  benzene, 
and  carbon  bisulphide,  soluble  in  alcohol,  less  soluble  in  ether.  When 
strongly  heated,  it  distils  without  alteration  ;  ignited  on  platinum  foil, 
it  burns  with  an  odor  of  burnt  wax.    It  is  but  slowly  attacked  by 
