ON  TOBACCO. 
215 
base,  provided  no  lengthy  evaporation  has  been  made  use  of,  in 
preparing  liquors  for  precipitation  with  mercury. 
The  ethereal  solution  obtained  in  this  manner  from  precipitates 
of  nicotina  at  first  leaves  the  alkaloid  as  a  pale,  yellowish,  oily 
liquid,  surrounded  by  a  greenish  brown  soft  resin  or  impure  wax, 
which,  next  to  ammonia,  is  the  cause  of  the  pungent  odor  of  to- 
bacco. To  a  certain  extent  it  is  a  product  of  the  oxidation  of 
the  alkaloid,  but  when  repeatedly  dissolved  in  alcohol  it  is  odor- 
less and  tasteless,  and  contains  no  nitrogen. 
Pure  nicotina  obtained  from  the  second  or  third  solution  in 
ether  is  colorless,  has  no  odor  at  first,  but  acquires  the  pungency 
and  odor  of  tobacco  after  some  hours'  exposure  to  the  air,  or  on 
being  heated.  It  agrees  in  most  respects  with  the  description 
given  by  Henry  and  Boutron-Charlard.  Half  a  drop  of  it  in- 
stantly killed  a  full-grown  pigeon. 
The  liquids  from  which  the  precipitate  of  nicotina  with  mer- 
cury had  been  obtained,  and  which  contained  an  excess  of  iodide, 
were,  after  filtering,  rendered  alkaline  by  the  addition  of  caustic 
potassa.  This  causes  a  decided  precipitate  only  in  the  case  of 
commercial  tobacco  ;  the  solutions  from  the  dried  leaves,  in  both 
the  above  experiments,  gave  a  faint  cloudiness.  The  filtrate 
from  the  seeds  did  not  even  show  a  trace  of  what  would  have  in- 
dicated the  presence  of  ammonia. 
The  precipitate  produced  in  the  first  case  was  decomposed  by 
alkali  and  protoxyd  of  tin,  and  then  distilled  ;  the  distillate  was 
converted  into  a  plantinum  salt,  which  had  all  the  properties  of 
that  of  ammonia. 
Having  become  satisfied,  by  my  preliminary  examination,  that 
no  stronger  alkali  than  ammonia  was  required  to  expel  nicotina 
as  well  as  trimethylina,  parts  of  the  solutions  to  which  no  mer- 
cury had  been  added  were  severally  distilled  with  caustic  ammo- 
nia. 
In  the  case  of  the  acid  infusion  of  fresh  tobacco,  no  bases  be- 
sides ammonia  (from  the  retort)  -  and  nicotina  were  to  be  found 
in  the  gases  and  the  liquids  which  came  over  and  were  received 
in  hydrochloric  acid.  Evaporated  to  dryness,  and  tested  for 
trimethylina,  no  traces  of  it  could  be  discovered  by  the  reactions 
described  above,  nor  any  particular  resemblance  in  the  odor  ; 
nor  could  any  inflammable  gas  be  extracted  from  the  residual 
chlorides  on  heating  with  caustic  potassa  or  baryta. 
