74  Extr actum  Ipecacuanha  Liquidum.    { Apebraar^ law?" 
excess  of  solution  of  ammonia  is  added,  and  the  alkaloids  are  re- 
moved by  shaking  with  three  successive  quantities  of  25  c.c.  chloro- 
form. The  mixed  chloroformic  solutions  are  evaporated  in  a  tared 
dish,  the  residue  dried  below  8o°  C,  and  weighed  as  total  alkaloids. 
On  trying  the  above  process  on  a  sample  of  the  liquid  extract  I 
was  struck  by  its  complexity  and  by  the  length  of  time  required 
for  its  completion.  Twenty  c.c.  of  liquid  extract  required  about  7 
c.c.  of  the  official  solution  of  subacetate  of  lead  for  complete  pre- 
cipitation, and  a  magma-like  mass  resulted,  which  filtered  very 
slowly  (taking  three  to  five  hours),  and  which,  even  after  having 
been  washed  as  thoroughly  and  carefully  as  possible,  still  contained 
a  considerable  quantity  of  alkaloid,  as  experiments  proved. 
Two  separate  assays  of  20  c.c.  of  the  liquid  extract  were  made 
by  the  official  process,  50  c.c.  of  water  being  used  to  wash  the  pre- 
cipitate obtained  on  adding  the  excess  of  lead  subacetate  solution. 
No.  1  assay  yielded  -386  alkaloidal  residue. 
No.  2  assay  yielded  .393  alkaloidal  residue. 
The  washed  lead  precipitates  were  then  examined  for  alkaloid,  as 
follows : 
The  precipitate  was  washed  from  the  filter  with  water,  decomposed 
with  excess  of  dilute  sulphuric  acid,  and  the  liquid  filtered  from  the 
sulphate  of  lead  into  a  separator.  Ten  c.c.  of  ether-chloroform 
were  then  added  and  the  mixture  agitated  ;  the  ether-chloroform 
was  allowed  to  separate  and  was  then  run  off  and  rejected.  This 
treatment  was  twice  repeated.  Excess  of  solution  of  ammonia  was 
then  added,  and  the  precipitated  alkaloids  removed  by  agitation 
with  successive  quantities  of  ether-chloroform.  The  mixed  ether- 
chloroform  solutions  were  evaporated  and  the  residue  dried  below 
8o°  C.  and  weighed. 
Precipitate  from  No.  1  assay  yielded  "031  gramme  alkaloidal  residue. 
Precipitate  from  No.  2  assay  yielded  '028  gramme  alkaloidal  residue. 
Not  only,  therefore,  is  the  official  process  from  the  nature  of  the 
lead  precipitate  tedious  to  perform,  but  it  is  inaccurate,  since  it  in- 
volves loss  of  alkaloid. 
A  number  of  experiments  were  then  made  with  the  object  of 
devising  a  simpler,  quicker  and  more  accurate  method  of  assay,  as 
a  result  of  which  I  suggest  the  following  as  possessing  these  advan- 
tages : 
"  Take  20  c.c.  of  the  strong  liquid  extract,  dilute  with  20  c.c. 
