444 
Ge hemic  Acid. 
/Aru.  Jour.  Pharro. 
\  September,  1897. 
I.  0*2432  gramme  substance  yielded  0*5582  gramme  of  C02=62'59  per  cent.  C. 
"      0-0988       "        V!  H20=  4-51  "     «  H. 
II.  0-1140     "  "  "     0-2610      "       "  00,-62-45  "     "  C. 
"      0-0470       "        "  H26=  4-58  "     "  H. 
III.  0  2926    "  "  "     0-6739       "        "  C02=62-8i  "     "  C. 
'<  "     0-1166       9        "  H20=  4-42  "     "  EL 
From  the  average  of  the  above  analyses  the  formula  C13Hn05  was 
deduced,  the  percentage  of  carbon  would  be  63-16  and  of  hydrogen 
4-45.    Thus  for  comparison  : 
Calculated.  Found  =   I.  II.  III. 
0  =  63-16  62-59  62*44  62*81 
H-  4  "45  4"5i  4"58  4*42 
A  molecular  weight  determination  (which  would  be  of  great  as- 
sistance here),  after  the  method  of  Beckmann  (kryoscopic),  was 
found  impossible  because  of  the  insolubility  of  gelsemic  acid  in  the 
cold  solvents  employed  in  these  determinations,  with  the  exception 
of  phenol,  which,  however,  gave  abnormal  results,  due  probably  to 
molecular  action  between  the  two. 
Action  of  Phosphorus  Pentachloride . — Gelsemic  acid  was  cau- 
tiously fused  with  a  slight  excess  of  phosphorus  pentachloride  ;  to 
the  mass  water  was  added  slowly,  the  tube  being  kept  well  cooled 
with  ice.  After  standing  a  few  hours  a  white  mass  separated, 
which,  after  thoroughly  washing,  was  taken  up  into  as  little  hot 
alcohol  as  possible,  filtered  and  again  precipitated  in  an  excess  of 
water.  This  operation  was  repeated  several  times  in  order  to  re- 
move a  non-crystallizable  impurity  which  was  comparatively  in- 
soluble in  alcohol ;  finally  the  product  was  recrystallized  twice  from 
alcohol.  This  chloro-derivative  of  gelsemic  acid  melts  at  1900  C.  A 
chlorine  estimation  was  made  after  Carius.  00615  gramme  of 
substance  yielded  0  06 16  gramme  of  AgCl,  which  corresponds  to 
24-76  per  cent,  of  chlorine.  The  theoretical  replacement  of  two 
hydroxyl  groups  by  chlorine  would  give  us  25  per  cent,  of  the  lat- 
ter. This  proves  conclusively  that  we  have  replaceable  hydroxyl 
groups  present. 
Thus, 
C13H9  (OH)203  =  C13H9  (C1)A- 
Calculated,  CI  =  25  percent.    Found  CI  =  24-76  per  cent. 
Action  of  Acetic  Anhydride. — Gelsemic  acid  was  heated  with 
acetic  anhydride  and  anhydrous  sodium  acetate  in  a  flask  with  reflux 
