22  Molybdic  in  Sulphuric  Acid  as  a  test.  {AmjI™s*lA™' 
person's  life  or  liberty  was  depending  upon  his  testimony.  The  test  is 
not  characteristic  ;  there  are  many  other  organic  bodies  which  yield  the 
same  color  with  the  reagent,  and  the  presence  of  other  organic  matter 
does  materially  interfere  with  the  reaction,  varying  according  to  its 
character.  He  states  that  he  was  able  to  produce  the  reaction  with  a 
single  drop  of  tinct.  opii  or  tinct.  opii  camph.,  he  could  as  well  pro- 
duce the  same  reaction  with  any  other  tincture,  and  even  with  pure 
alcohol  ;  but  they  give  a  bright  purple  color,  changing  to  blue,  and  not 
the  maroon,  which  is  produced  by  pure  morphia,  and  similar  bodies. 
Mr.  Buckingham,  in  "  American  Journal  of  Pharmacy,"  1873,  P- 
150,  proposed  a  solution  of  molybdate  of  ammonium,  eight  grains,  in 
sulphuric  acid,  two  drachms,  as  a  test  for  some  organic  bodies,  giving 
a  table,  showing  the  changes  of  color  produced  by  the  most  important 
alkaloids,  and,  while  his  results  show  that  his  experiments  were  con- 
ducted with  care,  yet  he  overlooked  the  fact  that  those  colors  vary 
according  to  the  condition  under  which  the  test  is  applied.  Prescott, 
in  his  new  and  valuable  little  work  on  proximate  organic  analysis,  p. 
144,  devotes  much  space  to  Frcehde's  reagent,  which  is  a  solution  of 
molybdate  of  sodium,  O'Oi  grain,  in  concentrated  sulphuric  acid,  10  cc, 
and  gives  a  table  showing  the  reaction  with  the  reagent,  and  with  pure 
sulphuric  acid.  I  do  not  think  that  the  indications  wnich  he  presents 
there  were  proven  with  proper  care ;  he  states  that  morphia  is  colorless 
with  concent,  sulphuric  acid — it  gives  a  wine-red  color.  These  test 
solutions  of  molybdic  acid,  or  molybdates  in  sulphuric  acid,  all  give 
like  reactions,  (varying  slightly  in  intensity  of  color).  My  experiments 
prove  them  to  be  unreliable,  and  therefore  worthless,  for  determining 
the  presence  of  the  alkaloids  ;  for  instance,  pure  quinia  gives  little  or 
no  color,  but  some  of  its  salts  at  once  yield  a  reaction  ;  bromide  and 
iodide,  deep  blue  ;  ferrocyanide,  red  ;  tannate,  red-brown. 
The  maroon  color  which  Dr.  Southey  produced  with  morphia,  and 
is  produceable  with  other  bodies,  is  caused  by  the  red  color,  given  with 
the  sulphuric  acid,  blending  with  the  blue  hydrate  of  molybdenum, 
which  is  formed  by  the  reduction  of  molybdic  acid  and  the  molybdates, 
when  brought  in  contact  with  certain  organic  matters  ;  the  variable 
green  color  is  produced  by  blending  with  the  yellow  color  given  to 
many  organic  bodies  by  the  action  of  sulphuric  acid,  and  when  these 
solutions  produce  a  red,  yellow  or  brown  coloration,  with  an  organic 
principle,  the  reaction  is  simply  with  the  sulphuric  acid,  the  molybdates 
taking  no  part  in  it. 
