Am.  Jour.  Pharm.) 
October,  1906.  J 
Some  Aikaloidal  Assays. 
459 
no  other  basic  substance  is  present  in  the  ethereal  solution.  If 
ammonia  be  used  to  set  the  alkaloid  free  there  will  be  large  quanti- 
ties of  the  volatile  alkali  in  the  ethereal  solution  and  the  latter  will 
have  to  be  distilled  to  dryness  or  at  least  to  small  bulk  in  order  to 
remove  the  last  trace  of  ammonia  which,  having  a  much  smaller  mo- 
lecular weight  than  most  alkaloids,  would,  if  not  completely  removed, 
vitiate  the  results  obtained  by  residual  titration.  But  if  instead  of 
ammonia  sodium  carbonate  or  sodium  hydroxide  be  used  for  liber- 
ating the  alkaloids,  we  can  always  make  use  of  such  an  immiscible 
solvent  which  does  not  take  up  any  trace  of  fixed  alkali  and  which 
will,  therefore,  contain  no  other  basic  substance  except  minute  traces 
of  ammonia  formed  by  the  action  of  the  fixed  alkali  upon  the  albu- 
minous matter  of  the  drug.  Such  traces  of  ammonia  can  be  easily 
and  quickly  removed  either  by  drawing  air  over  the  surface  of  the 
ethereal  liquid  or  more  quickly  by  concentrating  the  ethereal  solution 
upon  a  warm  water-bath  to  about  one-half  of  its  original  volume. 
As  immiscible  solvent  in  these  methods  ether  alone  cannot  be  used 
because,  dissolving  water,  ether  takes  up  some  fixed  alkali  when 
shaken  with  an  alkaline  solution.  But  if  instead  of  ether  alone, 
chloroform  alone,  or  a  mixture  of  three  volumes  of  ether  and  one 
volume  of  chloroform,  or  a  mixture  of  two  or  three  volumes  of  ether 
and  one  volume  of  petroleum,  ether  be  shaken  up  with  a  solution 
of  a  fixed  alkali  no  trace  of  alkali  goes  into  the  immiscible  solvent 
even  if  the  alkaline  solution  contains  50  or  60  per  cent,  alcohol. 
This  can  be  shown  by  filtering  the  immiscible  solvent,  after  shaking 
it  with  the  alkaline  solution,  through  a  plain  filter  of  ordinary  1 
filter  paper,  having  four  folds  on  each  side  and  previously  moistened 
with  ether,  and  then  shaking  up  the  ethereal  liquid  with  a  little 
water.  Neither  phenolphtalein  nor  any  other  delicate  indicator  will 
show  the  presence  of  alkali  in  the  aqueous  liquid. 
In  using  these  assay  methods  ordinary  vessels  may,  of  course, 
be  used.  But  the  sources  of  error  involved  in  transferring  ethereal 
liquids  from  one  vessel  to  another  can  be  eliminated  by  making  use 
of  the  two  following  special  separating  funnels. 
By  means  of  separating  funnel  No.  1  aqueous  and  ethereal  liquids 
can  be  drawn  off  through  separate  outlets  and  the  contamination  of 
1  Ordinary  filter  paper  is  a  better  absorber  of  moisture  and  therefore  of  traces 
of  adhering  alkali  than  the  filters  used  for  quantitative  analysis. 
