440  Gelsemic  Acid.  {TeA*%?/ 
Solubility. — G.  A.  is  soluble  I  p.  in  1490  of  distilled  water  at  300  C. 
"    "      "      1  p.  "    415  of  abs.  ether        "  220  C. 
"    "      "       I  p.  "    135  of  chloroform      "  240  C. 
Readily  soluble  in  hot  alcohol  and  glacial  acetic  acid. 
The  above  figures  show  the  average  of  three  careful  determina- 
tions each. 
Color  Tests. — The  reagents  employed  were  first  tested  for  such 
impurities  as  might  influence  the  color  reaction. 
(1)  With  cone.  H2S04  ==  pale  yellow,  disappears  on  standing. 
(2)  With  cone.  H2S04  warmed  =  deep  yellow. 
Professor  Wormley  obtains  a  yellow  to  red-brown  color  with 
above. 
(3)  With  cone.  H2S04  and  trace  of  HN03  =  blood  red,  quickly 
fades. 
(4)  With  cone.  H2S04  and  K2Cr207  =  to  yellow,  pale  violet, 
changing  to  green. 
Dr.  Robbins  obtains  no  reaction  with  4. 
(5)  With  cone.  H2S04  and  ammonium  molybdate  =  yellow ;  on 
standing  from  ten  to  twenty  minutes  ==  intense  blue  (hastened  if 
warmed). 
The  reaction.  5  is  very  delicate  and  characteristic. 
(6)  WTith  cone.  HN03  =  yellow;  if  G.  A.  is  in  excess  =  reddish 
color ;  to  this  add  NH4OH  in  excess  ==  intense  blood-red  color. 
Above  test  of  Wormley  is  sensitive  to  0-00002  gm. 
Reactions  in  Solution. — (1)  G.  A.  is  readily  soluble  in  diluted 
aqueous  solutions  of  the  caustic  alkalies  ;  the  resulting  solution  is  of 
a  pale  yellow  color  when  viewed  by  transmitted  light ;  by  reflected 
light  it  exhibits  an  intense  bluish-green  fluorescence,  I  part  in 
1,000,000  being  distinctly  fluorescent.  This  is  destroyed  by  addition 
of  acids. 
(2)  An  aqueous  solution  of  G.  A.  liberates  iodine  from  iodic  acid 
(HIOs). 
(3)  An  aqueous  solution  of  G.  A.  on  addition  of  ferric  chloride 
gives  a  green-colored  solution. 
(4)  Lead  acetate  and  mercuric  chloride  both  produce,  with  aque- 
ous solutions  of  G.  A.,  yellowish  precipitates  called  by  Robbins 
"  gelsemates."  These  precipitates  proved  to  be  a  mixture  of  basic 
hydroxides  of  the  metal  and  unaltered  gelsemic  acid,  the  latter 
being  readily  removed  by  washing  with  hot  water  or  alcohol. 
