^VufriJsTr'l        Ethereal  Solution  of  Quinia.  305 
tate  the  quinia,  and  in  order  to  avoid  too  great  an  excess  of  aqua  am- 
monite, it  is  best  to  make  a  preliminary  trial  of  the  dilute  sulphuric 
acid  and  aq.  ammonise  to  be  employed  in  the  process.  Introduce  into 
a  graduate  1  fl.  oz.  of  the  dilute  acid,  add  some  strips  of  litmus  paper, 
and,  while  stirring,  drop  in  very  gradually  from  another  graduate  (or 
burette)  aqua  ammonia,  until  the  litmus  paper  turns  blue.  The 
amount  of  aq.  ammonia  used  is  the  quantity  necessary  to  saturate  1 
fl.  oz.  of  the  acid.  Now  pour  upon  the  solution  in  the  4  pint  bottle 
a  little  more  than  double  the  amount  of  aqua  ammonia,  corresponding 
to  the  amount  of  dil.  sulphuric  acid  used,  in  order  to  precipitate  the 
quinia  ;  for  it  is  not  only  necessary  to  neutralize  the  amount  of  acid 
added,  but  also  the  other  equivalent  already  contained  in  the  original 
sulphate  of  quinia.  Immerse  the  bottle  in  ice-cold  water  to  absorb 
the  heat  generated  during  precipitation.  Have  a  sound  and  tightly 
fitting  cork  ready,  through  which  are  passed  two  narrow  glass  tubes, 
one  of  them  nearly  reaching  to  the  bottom  of  the  4  pint  bottle,  the 
other  just  penetrating  the  cork,  and  both  cut  olf  at  an  even  height  on 
the  upper  side.  When  the  bottle  has  been  sufficiently  cooled,  pour 
into  it  15  il.  oz.  of  stronger  ether  and  shake  ;  the  quinia.will  be  dis- 
solved, and  the  contents  of  the  bottle  will  arrange  themselves  in  two 
transparent  layers,  the  lower  one,  an  aqueous  solution  of  sulphate  of 
ammonia  (holding  a  little  ether,  and  also  a  trace  of  quinia  in  solution) 
and  the  upper  one,  an  ethereal  solution  of  quinia.  Introduce  the  cork 
into  the  mouth  of  the  bottle,  keeping  the  finger  on  the  orifices  of  the 
glass  tubes,  and  invert  the  bottle.  Hold  it  for  a  short  time  in  a  some- 
what inclined  position,  to  allow  the  watery  solution  adhering  to  the 
sides  and  bottom  to  drain  down  into  the  lower  layer  ;  then  remove  the 
finger  and  allow  the  lower  layer  to  flow  off  into  a  vessel  placed  below. 
As  soon  as  the  line  of  demarkation  approaches  the  cork,  allow  the 
liquid  to  pass  only  very  gradually,  and  as  soon  as  all  the  aqueous  so- 
lution has  run  ofl',  receive  the  ethereal  solution  in  a  16  oz.  graduate. 
Rinse  the  bottle  with  J  fl.  oz.  of  ether  and  add  it  to  the  former.  Allow 
the  ethereal  solution  to  evaporate  in  a  warm  place  (110 — 120°  F.) 
until  reduced  to  2J  fl.  oz.  Remove  it,  cover  it  well,  to  prevent  fur- 
her  evaporation,  and  cool  it  to  the  temperature  of  60°F.  Then  measure 
off  into  a  weighed  graduated  tube  (or  minim  graduate)  5  minims  and 
evaporate  to  dryness.  Should  there  be  no  scales  sufficiently  accurate 
to  indicate  fractions  of  a  grain,  use  an  aliquot  multiple  of  5  minims, 
f.  i.  50  minims,  in  which  case,  of  course,  you  will  have  to  divide  after- 
20 
