326 
Thapsia  Resin. 
[Am.  Jour.  Pharm. 
I       June,  1884. 
bromine  or  by  strong  nitric  acid.  It  is  a  bibasic  acid.  Its  potassium 
sail,  C16H2S04K2,  forms  shining  anhydrous  prisms.  The  barium  salt, 
C16H2S04Ba,  obtained  by  precipitation  from  the  potassium  salt,  is  a 
white  amorphous  powder  insoluble  in  water  and  very  slightly  soluble 
in  boiling  alcohol.  The  silver  salt,  C16H2s04Ag2,  is  a  white  insoluble 
precipitate  which  blackens  when  heated  or  exposed  to  light. 
Thapsic  acid  dissolves  at  boiling  heat  in  aqueous  ammonia,  and  the 
solution  on  cooling  deposits  a  crystalline  substance  probably  consisting 
of  the  corresponding  amide.  The  acid  heated  with  aniline  at  170 — 
180°  in  sealed  tubes,  is  converted  into  the  anilide,  C16H2S02(NHPh)2, 
which  forms  a  white  crystalline  powder  melting  at  162 — 163°,  and 
acquiring  a  faint  violet  color  when  exposed  to  the  air. 
The  barium  salt  of  thapsic  acid  distilled  at  a  moderate  heat  with 
excess  of  barium  hydroxide,  yields  a  small  quantity  of  hydrocarbons, 
saturated  and  non-saturated,  having  a  musky  odor,  combining  for  the 
greater  part  with  bromine,  and  forming  a  solid  body  which  when 
dried  between  bibulous  paper  and  crystallized  from  alcohol,  forms 
white  needles  melting  at  73°. 
Octoic  or  Caprylic  Acid,  C8H1602. — On  distilling  with  steam  the 
oily  precipitate  obtained  by  neutralizing  with  hydrochloric  acid  the 
potash  solution  of  the  ethereal  extract  of  the  resin,  after  removal  of 
potassium  thapsate  and  dilution  with  water,  there  passes  over  a  yellow 
transparent  oil,  lighter  than  water.  On  exhausting  this  oil  with 
ether,  drying  the  etheric  solution  with  calcium  chloride  and  distilling, 
the  greater  part  goes  over  at  220 — r236° ;  and  on  fractioning  this 
portion  at  intervals  of  5 — 5°,  three  other  fractions  are  obtained,  the 
most  abundant  of  which  is  a  colorless  liquid  soluble  in  alcohol  and 
ether,  and  solidifying  when  cooled  with  snow,  in  flexible  lamina?  melt- 
ing at  ordinary  temperatures.  The  product  thus  obtained  is  shown  by 
analysis  to  have  the  composition  of  an  octoic  acid,  and  in  its  melting 
and  boiling  points  it  agrees  nearly  with  the  octoic  acid  obtained  by 
saponification  of  cocoanut  oil,  and  by  oxidation  of  the  octyl  alcohol 
from  heracleum  oil,  melting  at  16°,  boiling  at  236 — 237°,  which 
agreement  the  author  has  further  confirmed  by  examination  of  the 
sodium,  barium,  and  zinc  salts.1 
The  author  suggests  that  thapsic  acid  may  be  a  dioctoic  acid, 
C8H1502.C8H1502  —  2C8H1604  —  H2,  formed  from  the  octoic  acid  by 
slow  oxidation  in  the  body  of  the  plant. —  Gazetta,  13,  514-521 ;  Jour. 
Ckem.  Soc,  April,  1884,  p.  460. 
1  The  octyl  alcohol  of  heracleum  oil  is  an  iso-alcohol,  CHMe2(CH2)4.CH2OH, 
and  consequently  the  acid  obtained  from  it  by  oxidation  must  be  an  iso- 
acid,  CHMe2(CH2VCOOH.    (See  Watts'  Dictionary  of  Chemistry,  8,  379.) 
