240 
ACTION  OF  CARBONIC  ACID  UPON  QUININE,  ETC. 
nine  at  so  low  a  temperature  furnishes  a  ready  means  for  its 
analysis  in  the  following  manner : — A  glass  tube,  12  or  15  cen- 
tims.  in  length,  and  closed  at  one  end,  was  weighed,  and  0*399 
grm.  of  carbonate  of  quinine  introduced  into  it.  It  was  then 
connected,  by  means  of  a  cork  covered  with  india-rubber,  with  a 
bent  tube,  which  passed  under  a  graduated  bell-glass  placed  over 
some  mercury  in  a  test-glass.  The  extremity  of  the  tube  passed 
the  surface  of  the  metal,  so  as  to  reach  into  the  empty  part  of 
the  bell-glass  intended  for  the  reception  of  the  carbonic  acid  gas. 
The  closed  tube  containing  the  salt  was  then  heated  in  the  oil- 
bath  to  about  230°  F.  Just  before  this  temperature  is  reached, 
the  carbonate  of  quinine  is  decomposed,  the  carbonic  acid  being 
driven  off  without  any  sensible  change  being  produced  .  in  the 
physical  characters  of  the  salt. 
The  339  milligrms.  of  the  salt  employed  in  this  experiment 
furnished  21-36  cub.  centims.  of  carbonic  acid  gas  at  32°  F., 
and  a  pressure  of  76  centims.  This  volume  of  gas  weighs 
0-0422  grm.  The  evolution  of  gas  ceases  long  before  the  oil- 
bath  reaches  the  temperature  of  338°  F.,  at  which  the  quinine 
fuses  and  entirely  loses  its  water.  The  moisture  which  adheres 
to  the  side  of  the  tube  is  readily  removed  by  means  of  a  few 
pieces  of  blotting-paper.  The  weight  of  the  quinine,  obtained 
by  weighing  the  tube  after  the  experiment  and  deducting  the 
weight  of  the  empty  tube,  was  321  milligrms.  0-399  grm.  of  car- 
bonate of  quinine  consequently  furnished — 
per  cent. 
Grm.         Found.  Calculated. 
Quinine  0-3210       80-45  80-21 
Carbonic  acid  0-0422       10-58  10-88 
Water  0-0358        8-97  8-91 
These  numbers  lead  to  the  formula  (C20  H12  NO2,  HO)  CO2 
HO  for  this  salt.  Six  successive  experiments  on  different  quan- 
tities of  the  salt  all  led  to  the  same  results.  As  it  must  be  re- 
garded as  neutral,  we  thus,  in  ascertaining  its  composition,  fix 
the  equivalent  of  quinine,  which  in  this  case  agrees  with  that  ad- 
mitted by  Leibig. 
This  decomposition  of  carbonate  of  quinine  at  a  low  tempera- 
ture has  also  shown  that  this  salt  is  not  formed  by  double  decom- 
position when  a  saline  solution  of  quinine  is  treated  with  a  solu- 
tion of  carbonate  of  potash  or  soda.    The  precipitate  formed 
