196  •  Identification  of  Cocaine.  {^'^'£y\^i'''^' 
according  to  Autenrieth.^  This  test  is  not  reliable,  however,  as 
it  is  also  given  by  alpha-  and  beta-eucaine,  stovaine  and,  in  fact, 
by  any  of  the  cocaine  substitutes  containing  the  benzoyl  group. 
The  tests  which  fulfilled  our  requirements  most  satisfactorily, 
and  which  we  adopted  in  our  work,  are  based  upon  the  following 
observations.  Cocaine  salts  will  react,  under  certain  conditions, 
with  gold  chloride,  platinum  chloride,  chromic  acid  and  potassium 
Fig.  I. 
Cocaine  chloro-platinate,  x  100. 
permanganate  to  form  precipitates  which,  when  examined  under 
the  microscope,  are  found  to  possess  definite  and  characteristic 
crystalline  forms. 
The  test  solutions  required  are — i  per  cent,  solutions  of  gold 
chloride,  platinum  chloride  and  potassium  permanganate  and  a  5 
per  cent,  solution  of  chromic  acid. 
The  alkaloid,  isolated  in  the  usual  ways,  is  converted  into  the 
hydrochloride  and  made  up  to  a  2  per  cent,  solution.   A  small  por- 
^  Autenrieth,  Auffindung  der  Gifte,  3  Aufl.,  page  79. 
