Am.  Jour.  Phafm.  I 
July,  1910.  f 
Analysis  of  Ointments. 
317 
used  for  this  purpose.  A  residue  remaining  may  be  used  for  quali- 
tative analysis. 
Qualitative  Analysis. — Metals. — Three  to  five  grammes  of 
the  ointment  are  reduced  to  ash  in  a  porcelain  crucible  and  the  resi- 
due tested  for  metals  in  the  usual  way.  It  is  a  precautionary  rule 
not  to  use  a  platinum  crucible  as  the  presence  of  lead  (lead  plaster, 
etc.)  might  damage  the  crucible.  Mercury  and  its  salts  and  arsenic, 
if  they  are  present  are  volatilized,  as  are  also  certain  salts  of  zinc  and 
lead,  which  are  more  or  less  volatile. 
Reinsch's  test  for  arsenic  and  mercury.  About  three  grammes 
of  the  ointment  are  boiled  gently  for  five  minutes  with  5  c.c.  of  con- 
centrated hydrochloric  acid  and  5  c.c.  of  water,  having  immersed 
previously  a  piece  of  clean  bright  copper  foil.  If  the  copper  foil, 
after  a  lapse  of  five  minutes,  still  presents  the  same  appearance  as  it 
had  before,  no  arsenic  or  mercury  can  be  present.  Should  the 
copper  foil,  however,  show  a  steel-gray  deposit  or  appear  lustrous- 
like  silver,  arsenic  or  mercury  are  apparently  present.  The  copper 
foil  is  removed,  washed  with  water,  dried  with  filter  paper  and 
cautiously  heated  in  a  perfectly  dry  narrow  glass  tube,  open  on  both 
ends.  The  sublimate  will  collect  on  the  cooler  portion  of  the  tube. 
Arsenic  is  converted  into  arsenous  acid,  its  tetrahedral  or  octahedral 
crystals  are  apparent  under  the  microscope.  A  sublimate  of  mercury 
will  be  found  to  consist  of  very  small  globules.  The  hydrochloric 
acid  used  in  this  test  must  be  free  from  arsenic.  Oxidizing  agents, 
such  as  nitrates,  will  interfere  with  the  reaction. 
Another  method  to  test  for  metals  (except  silver)  and  acids  is 
as  follows :  Five  grammes  of  the  ointment  are  repeatedly  shaken 
with  hot  diluted  hydrochloric  acid,  filtered,  after  cooling,  through 
a  moistened  filter  and  the  filtrate  tested.  Part  of  the  filtrate  may  be 
dried  down  on  the  water  bath  to  see  if  anything  be  left  behind. 
Alkaloids  and  Narcotic  Extracts. — Alkaloids. — A  sufficient 
quantity  of  the  material  is  vigorously  shaken  with  hot  very 
dilute  sulphuric  acid,  allowed  to  cool  and  filtered  through  a  filter 
moistened  with  water.  A  portion  of  the  filtrate  is  examined  with 
two  or  three  of  the  general  reagents  for  the  alkaloids,  such  as  solu- 
tion of  iodine,  phosphomolybdic  acid  or  Meyer's  reagent.  Should 
a  turbidity  or  precipitate  form,  the  presence  of  alkaloids  is  suspected. 
The  acid,  aqueous  filtrate  is  slightly  supersaturated  in  a  separating 
funnel  with  ammonia  and  the  ammoniacal  liquid  extracted  by  shak- 
ing with  chloroform,  the  latter  is  allowed  to  separate,  removed 
