AmFe°buri8P76arm:}  Frcehdes  Reagent  a  Test  for  Morphia.  61 
the  organic  products  of  the  oxidation,  and  this  has  been  the  case  with 
some  so  definite  as  to  have  a  quantitative  application  (such  as  the  use 
of  the  potassic  cupric  tartrate).  No  one  of  these  tests  is  good  for  any- 
thing unless  applied  to  carefully  classified  material.  Thus,  Froehde's 
reagent  is  directed  to  be  applied  to  alkaloids,  "  absolutely  free  from 
impurities,  not  alkaloids."  Salts  of  alkaloids  with  acids  which,  liberated 
by  the  sulphuric  acid,  will  act  as  oxidizing,  or  reducing,  or  coloring 
agents,  are,  of  course,  unsuitable  forms  for  the  test.  So  it  is  not 
strange  that  Mr.  Wellcome  obtained  the  colors  he  names,  with 
bromide,  iodide,  ferrocyanide  and  tannate,  of  quinia. 
The  extreme  dilution  of  the  molybdic  acid  in  DragendorfPs  use  of 
Froehde's  reagent,  shows  the  intensity  of  that  elective  reducing  power 
possessed  by  some  alkaloids,  and  renders  this  form  of  the  reagent  much 
more  reliable  than  the  form  used  by  Buckingham  (the  strength  first 
proposed  by  Froehde,  being  intermediate).  Stannous  chloride  solution 
quickly  colors  ordinary  molybdate  solutions  blue,  but  this  and  most 
other  inorganic  reducing  agents  fail  to  affect  the  solution  when  it  is  of 
the  strength  that  DragendorfF  uses. 
There  yet  remains  to  consider  a  statement  in  Mr.  Wellcome's 
paper,  concerning  a  point  of  much  importance  in  the  identification  of 
morphia,  a  point  having  some  practical  relations  generally  overlooked. 
Referring  to  the  table  of  reactions  with  Froehde's  reagent  given  in 
"  Outlines  of  Proximate  Organic  Analysis,"  and  to  the  statement  there 
that  morphia  with  concentrated  sulphuric  acid  alone  is  colorless,  he  reports 
that  "it  gives  a  wine-red  color."  If  the  latter  statement  is  correct,  it 
certainly  greatly  weakens  the  evidence  of  the  violet  color  obtained 
when  the  trace  of  molybdate  is  present.  And,  if  my  reader  leaves  this 
discussion  to  try  the  test  for  himself,  with  the  first  materials  at  his 
hand,  he  may,  probably,  find  in  a  few  minutes  the  result  (even  in  the 
cold)  which  Mr.  Wellcome  found.  If  so,  and  he  is  sure  that  his 
sulphuric  acid  is  absolutely  pure,  and  his  morphia  or  its  sulphate  pure, 
so  much  the  worse  for  Froehde's  reagent  and  its  authorities  ;  while,  if 
he  is  not  sure  of  the  absolute  purity  of  his  materials,  the  result  suggests 
caution  in  use  of  the  test,  and  inquiry  as  to  impurities  and  their  influence. 
The  authorities  are  nearly  uniform  in  the  statement  that  morphia  is 
not  colored  by  concentrated  sulphuric  acid  (in  the  cold  and  without 
