124  Laboratory  Notes  on  Assay  Work.  ("'Sj™1, 
During  the  last  year  we  found  some  lots  of  sanguinarine  nitrate 
to  contain  a  considerable  amount  of  aniline  colors,  and  at  the  same 
time  to  assay  extremely  low ;  one  sample  assayed  only  52  per  cent, 
pure  sanguinarine  nitrate.  With  the  exception  of  a  small  amount 
of  moisture,  the  remainder  consisted  mainly  of  some  potassium 
nitrate  and  sugar  of  milk.  As  the  U.  S.  P.  requires  no  assay  of 
sanguinarine  and  its  preparations  it  would  be  of  no  great  interest 
to  the  pharmacist  at  present  to  go  into  further  details. 
Gelsemium  is  another  drug  for  which  no  assay  is  required  by 
the  U.  S.  P.,  but  as  this  drug  is  employed  now  quite  extensively  it 
seems  to  be  worth  while  to  say  a  few  words  in  regard  to  its  assay. 
In  our  laboratories  we  assay  this  drug  and  preparations  derived 
therefrom  chemically  as  well  as  physiologically.  Shaken  out  by  the 
old-style  method,  the  gelsemine  mostly  contains  a  large  amount  of 
highly  colored  foreign  matter,  which  makes  a  gravimetric  deter- 
mination nearly  impossible,  while  the  coloring  matter  interferes  with 
the  volumetric  end  reaction.  We  did  not  have  any  difficulty  in 
getting  rid  of  the  coloring  matter  by  precipitation  with  solution  of 
lead  subacetate  followed  by  dried  and  powdered  sodium  phosphate 
or  sulphate,  and  were  satisfied  with  the  results  in  comparison  with 
those  obtained  by  other  reliable  methods.  Only  lately,  we  also  tried 
Webster's  method  (tartaric  acid)  modified  by  Sayre  and  got  good 
results  on  comparison. 
The  assays  made  by  the  latter  method  came  out  a  trifle  higher 
than  those  made  by  our  own  method.  The  main  advantage  of  the 
new  method  lies  in  the  fact  that  the  recovered  alkaloid  has  a  much 
lighter  color  than  that  recovered  by  the  old  methods,  and  therefore 
the  alkaloidal  residue  is  easily  titrated,  using  either  iodeosin  or 
cochineal  as  indicator.  We  are  now  using  the  Webster-Sayre 
method  exclusively. 
On  assaying  physostigma  preparations,  we  employ  both  the 
gravimetric  and  volumetric  methods  as  a  check.  If  the  assays  are 
carried  out  lege  artis  both  will  compare  favorably.  If  the  alkaloidal 
residue  is  brown  or  dark  colored  the  gravimetric  method  will  give 
in  most  cases  results  which  are  'much  too  high ;  on  the  other  hand, 
it  is  very  difficult  to  get  a  sharp  end  reaction  with  iodeosin,  etc.,  as 
indicators,  if  the  acid  solution  of  the  alkaloid  is  highly  colored.  If 
both  assays  compare  well  we  are  certainly  satisfied ;  if  not,  we  make 
these  assays  over  until  good  results  are  obtained.  As  physostigma 
deteriorates  very  rapidly,  even  more  so  on  exposure  to  light,  air  and 
