IDENTITY  OF  ACONELLA  WITH  NARCOTINA. 
341 
and  stir  one  part  with  a  glass  tube  dipped  in  dilute  nitric  acid, 
repeating  the  addition  of  this  acid  by  means  of  the  tube,  until 
the  liquid  becomes  perfectly  red.  Then  mix  it  with  the  other 
portion  which  has  remained  blue.  The  result  is  a  reddish  blue 
liquid.  A  litmus  dye  is  thus  obtained  as  neutral  as  possible, 
which  must  then  be  evaporated  in  a  porcelain  capsule,  placed 
in  a  sand-bath,  and  kept  below  boiling  point.  There  remains  a 
granular,  amorphous  mass,  which  must  be  kept  in  a  well  stop- 
pered bottle.  This  matter  dissolves  in  water,  leaving  no  resi- 
due, and  gives  a  lighter  or  darker  blue  according  to  the  quan- 
tity of  water  used,  and  has  the  advantage  of  furnishing  a  lit- 
mus dye  at  a  moment's  notice,  and  at  any  degree  of  concentra- 
tion which  may  be  required.  If,  for  instance,  it  is  desired  to 
experiment  with  a  standard  solution,  a  piece  of  the  above  ex- 
tract, about  the  size  of  a  pin's  head,  put  in  a  wine  glass  con- 
taining a  little  water,  will  yield  a  very  convenient  solution. 
This  extract  may  be  preserved  in  closed  vessels  for  years  with- 
out losing  either  its  solubility  or  its  blue  color  Chem.  News, 
London,  April  31,  1864.,  from  Journal  de  Pharmacie  et  de 
Chemie,  xlv.  70.  64. 
IDENTITY  OF  ACONELLA  WITH  NARCOTINA. 
Having  received  some  time  ago,  from  my  friend,  Mr.  H.  Dra- 
per, a  specimen  of  the  alkaloid  discovered  by  Messrs.  T.  and  H. 
Smith,  of  Edinburgh,  in  aconitum  napellus,  I  thought  it  proba- 
ble that  some  interesting  results  might  be  obtained  by  submit- 
ting a  solution  of  the  alkaloid  to  the  action  of  polarised  light. 
My  object  was  to  compare  the  change  in  the  plane  of  polariza- 
tion of  a  ray,  produced  by  transmission  through  a  tube  filled 
with  this  solution,  with  the  change  similarly  produced  by  a  so- 
lution of  narcotina.  This  I  was  enabled  to  do  with  very  great 
accuracy  by  means  of  an  instrument  which  I  described  at  a 
meeting  of  the  Royal  Irish  Academy  in  January,  1863. 
The  experiment  was  made  as  follows : — 
1.  I  dissolved  2-95  gr.  of^aconella  in  1|  cubic  inches  of 
chloroform,  and  determined  the  rotatory  power  of  the  solution. 
I  then  made  a  solution  of  narcotina  of  the  same  strength,  and 
