PAPERS  READ  AT  THE  BRITISH  PHARM.  CONFERENCE.  535 
cially,  that  was  suggested  as  the  safest  and  best  means  of  ob- 
taining the  dilute  acid  ;  and  the  combustion  of  phosphorus,  with 
arrangements  for  the  supply  of  air  and  collection  of  acid,  was 
suggested  as  the  best  mode  of  obtaining  such  a  pure  glacial 
acid.  Other  plans  for  its  preparation,  which  were  detailed,  had 
been  tried,  and  found  unsatisfactory. 
ON  THE  ASSAY  OF  THE  ALKALOIDS  IN  MEDICINAL  EXTRACTS. 
BY  T.  B.   GROVES,  F.C.S. 
The  object  of  the  author  was  to  devise  a  process  for  estimating 
the  strength  of  the  vegetable  extracts  used  in  medicine.  The 
method  he  employed  was  a  volumetric  one.  Mayer,  of  New 
York,  and  Valser,  of  Paris,  had  worked  upon  the  same  subject, 
and  all  three  had  fixed  upon  the  same  liquid  for  precipitating 
the  alkaloid  ;  namely,  the  iodo-hydrargyrate  of  potassium.  All 
three  also  had  suggested  formulae  for  the  precipitate.  Valser's 
experiments  corroborated  those  of  the  author,  while  Mayer's 
pointed  to  a  different  conclusion.  Mayer's  experiments  were 
then  reviewed,  and  the  details  of  some  reactions  given  from 
which  it  seems  that,  on  adding  the  iodo-hydrargyrate  to  the 
solution  of  the  alkaloid,  a  point  was  arrived  at  when  the  addi- 
tion of  either  liquid  caused  a  precipitate.  In  this  way  some  of 
the  apparent  anomalies  might  be  explained.  If,  however,  time 
were  allowed  for  the  completion  of  the  reaction,  more  definite 
results  might  be  obtained.  He  described  the  reactions  with 
strychnia,  quinine,  cinchonine,  morphia,  nicotina,  and  codeia, 
and  reviewed  Mayer's  results,  which  were  quite,  he  said,  ano- 
malous. In  estimating  the  amount  of  alkaloid  in  an  extract, 
the  alkaloid  must  first  be  isolated  as  far  as  possible,  by  Stas's 
well  known  method.  In  estimating  the  medicinal  value  of  an 
extract,  more  exact  methods  than  those  now  known  must  be 
discovered  before  accuracy  can  be  attained. 
ON  THE  PREPARATION  OP  AN  IMPROVED  WINE  OF  IRON. 
BY  H.  N.  DRAPER,  F.C.S. ,  AND    MR.  J.  WHITLA. 
The  authors  first  described  their  observations  of  the  action 
of  light  in  promoting  decomposition  of  the  officinal  wine  of  iron. 
To  prevent  this  decomposition,  which  occurs  even  in  the  dark, 
they  suggested  that  ammonia-citrate  of  iron  should  replace 
potassio-tartrate,  and  that  citrate  of  ammonia  should  also  be 
