236 
a-  and  fi-Eucaine. 
Am.  .Tour.  Pharm. 
May,  1902. 
THE  IDENTIFICATION  AND  PROPERTIES  OF  a-  AND 
,3-EUCAINE.1 
By  Charges  Lathrop  Parsons. 
( Concluded  from  page  342. ) 
MICROSCOPIC  CHARACTERISTICS. 
A  careful  examination  of  many  of  the  precipitates  which  the 
various  reagents  yield  with  either  of  the  eucaines  or  with  cocaine 
failed  to  disclose  any  special  characteristic  of  value.  Many  of  them 
are  beautifully  crystalline  and  give  striking  displays  of  color  with 
polarized  light,  but  they  vary  too  much  with  different  conditions  to 
be  used  with  certainty  as  a  means  of  identification.  An  examina- 
tion of  the  alkaloids  themselves  as  precipitated  by  ammonia  and 
crystallized  from  chloroform  also  give  negative  results.  Fortunately, 
however,  the  hydrochlorides,  when  pure,  are  easily  identified  under 
the  polarizing  microscope,  and  especially  is  cocaine  hydrochloride 
recognizable  at  once. 
The  slides  are  best  prepared  by  allowing  a  drop  of  an  aqueous 
solution  to  spontaneously  evaporate.  Cocaine  under  these  condi- 
tions does  not  always  crystallize  at  once  even  when  quite  dry.  But 
if  set  aside  for  a  few  hours  the  crystals  will  form  and  the  peculiar 
feathery  and  fan-shaped  radiations,  resembling  very  closely  those 
seen  on  a  broken  nodule  of  wavellite,  are  recognizable  even  with  the 
naked  eye.  The  examination  is  most  satisfactorily  performed  with 
a  magnifying  power  of  about  250  diameters. 
a-Eucaine  hydrochloride  in  saturated  solution  tends  to  crystallize 
in  little  spots  which,  under  polarized  light,  look  like  very  highly 
colored  rosettes  made  up  of  very  small  crystals,  so  that  the  field  is 
always  bright,  never  showing  any  constancy  of  extinction  directions. 
On  edges  of  drop,  the  rosettes  sometimes  show  small  feathery  forms 
of  crystals  of  which  the  extinction  directions  vary  but  are  more 
often  diagonal.  A  5  per  cent,  solution  gives  much  the  same  result. 
The  rosettes  frequently  appear  to  be  made  up  of  concentric  rings  of 
very  small  crystals,  the  centre  of  rosettes  being  thicker  than  edges, 
and  only  the  edges  showing  plate  or  feather  forms  large  enough  to 
be  examined  as  individuals.  Interference  colors  are  very  bright. 
When  crystallized  from  dilute   solution    the  rosette  forms  may 
1Read  at  the  Denver  meeting  of  the  American  Chemical  Society,  August  29,. 
1901,  and  reprinted  from  the  four.  Amer.  Chem.  Soc.,  1901,  p.  885. 
