^™ ■june'^im*'^™' }   ^^'^^  Permanganate  Test  for  Cocaine.  367 
loid  are  concerned,  in  favor  of  the  .gold  chloride  and  platinum 
chloride  tests.*^ 
Recently,  the  writer  has  studied  the  action  of  permanganate 
solutions  of  various  concentrations  upon  solutions  of  cocaine  for 
the  purpose  of  increasing,  if  possible,  the  delicacy  of  the  test. 
When  neutral  solutions  of  cocaine  were  used,  it  was*  found  that 
the  limit  of  precipitation  was  reached  when  the  solution  contained 
I  per  cent,  of  cocaine  hydrochloride  and  this  was  true  whether 
five  drops  of  a  i  per  cent,  or  i  c.c.  of  saturated,  permanganate 
solution  was  added. 
Acid  solutions  of  cocaine  hydrochloride  were  next  treated  with 
the  permanganate  solutions.  It  was  found  that  acidity  of  the 
liquid  favored  the  precipitation  of  cocaine  permanganate.  After 
several  trials  with  various  concentrations  of  acid  and  perman- 
ganate, acidity  corresponding  to  i  per  cent,  sulphuric  acid,  and  a 
volume  of  saturated  potassium  permanganate  equal  to  that  of  the 
cocaine  solution  yielded  the  best  results. 
The  test  as  now  used  in  this  laboratory  is  then  as  follows : 
To  I  c.c.  cocaine  solution,  add  one  drop  of  25  per  cent,  sulphuric 
acid  and  i  c.c.  saturated  potassium  permanganate  solution.  After 
standing  some  time,  a  drop  of  the  liquid  is  removed  to  a  slide, 
cover  glass  adjusted,  excess  of  liquid  removed  and  a  drop  of  water 
drawn  under  the  cover  glass  by  means  of  a  piece  of  filter  paper 
placed  on  the  opposite  side.  The  slide  is  then  examined  under  the 
microscope  for  the  characteristic  violet-red  rectangular  plates  of 
cocaine  permanganate. 
Working  in  the  manner  above  described,  the  writer  has  detected 
cocaine  in  i  c.c.  of  solution  which  contained  .00033  gram  cocaine 
hydrochloride,  equivalent  to  i  in  3,000. 
The  other  common  natural  alkaloids  and  cocaine  substitutes 
above  mentioned,  with  the  exception  of  A-  and  B-eucaine,  when 
treated  as  in  the  above  test  were  instantly  oxidized.  The  two 
eucaines  reduced  the  permanganate  very  slowly. 
A-eucaine  yielded  very  small  irregular  masses  of  violet-red 
leafy  crystals  in  i  per  cent,  solutions.  In  high  dilutions  (1:600) 
the  crystals  were  better  formed  and  resembled  those  of  ammonium 
magnesium  phosphate.  The  limit  for  the  formation  of  the  A-eucaine 
permanganate  crystals  is  i  :5ooo. 
"  See  Am.  Jour.  Phakm.,  Vol.  83,  p.  195. 
