308  PREPARATION,  PROPERTIES  AND  COMPOSITION  OP  EMETIA. 
ume  that  of  the  mixture.  As  emetia  is  very  soluble  in  potassa, 
and  as  the  alkaline  solution  absorbs  oxygen  rapidly  from  the 
air,  the  flask  in  which  the  reaction  is  effected  should  always  be 
full. 
The  mixture  is  agitated  violently,  and  left  to  repose  during 
many  days ;  the  chloroform,  which  forms  a  kind  of  emulsion, 
separates  little  by  little,  occupying  the  bottom  of  the  vessel. 
This  is  decanted  and  replaced  by  a  new  portion  of  chloroform. 
As  soon  as  the  washings  are  nearly  colorless,  they  are  united, 
filtered,  and  the  chloroform  regained  by  distillation,  by  aid  of  a 
water  bath  and  retort. 
The  residue  in  the  retort  is  deep  brown,  and  composed  princi- 
pally of  emetia  and  resinoid  matter,  which  last,  according  to  Pel- 
letier  and  Magendie,  is  not  emetic.  The  emetia  is  separated  by 
a  weak  acid,  which  dissolves  only  the  alkaloid.  The  solution  is 
then  decomposed  by  ammonia,  avoiding  any  excess,  as  emetia  is 
soluble  in  ammoniacal  water.  Emetia  is  then  deposited  as  a 
bulky  greyish  powder,  which  is  washed  with  distilled  water  by 
decantation,  and  collected  on  a  filter. 
It  is  finally  digested  with  ether,  to  remove  a  trace  of  resinoid 
matter,  and  dried,  when  the  alkaloid,  of  great  purity,  is  ob- 
tained. 
Properties,  When  it  has  been  precipitated  from  saline  solu- 
tions by  ammonia,  and  dried  at  a  temperature  below  133°  Fahr., 
emetia  presents  the  form  of  a  very  light  greyish  powder,  if  it  has 
not  been  perfectly  purified,  and  whitish  if  it  is  very  pure. 
It  is  nearly  odorless,  and  its  taste  bitter.  It  fuses  at  the  tem- 
perature of  158°  Fahr.,  and  assumes  the  form  of  a  brown  trans- 
parent extract. 
Exposed  freely  to  the  air  it  becomes  light  brown  colored,  but 
does  not  attract  humidity  so  as  to  become  liquid,  as  stated  by 
Pelletier  and  Magendie. 
At  59  Fahr.  water  dissolves  one-thousandth  of  its  weight,  and 
the  solution  possesses  always  a  yellowish  tint,  as  well  as  an  alka- 
line reaction.  Alcohol  and  chloroform  dissolve  it  in  all  propor- 
tions, and  it  never  crystallizes  by  their  evaporation.  It  is  but 
slightly  soluble  in  ether  and  the  fixed  oils.  Solutions  of  the  caus- 
tic alkalies  dissolve  it  very  readily,  and  the  solutions  rapidly  ab- 
