468  Alkaloids  of  Coca  Leaves.  {^'"'oct'ifss!''"' 
in  the  fixed  and  volatile  oils ;  nearly  insoluble  in  water.^  It  combines 
with  acids,  completely  neutralizing  them  and  forming  salts  which  are 
generally  easily  crystallizable. 
The  salt  of  cocaine  most  employed  is  the  hydrochlorate.  Although 
crystallizing  easily,  it  is  often  offered  in  the  form  of  an  amorphous 
powder,  and  such  a  product  is  not  of  necessity  impure.  The  salt, 
however,  should  be  nearly  white,  and  wholly  free  from  odor,  and 
should  show  no  disposition  to  absorb  moisture  from  the  air.  The  micro- 
scopic appearance  of  the  crystallized  pure  salt  is  shown  in  Fig.  3,  B, 
drawn  from  nature.  It  should  dissolve  easily  and  completely  in  water, 
yielding  a  colorless  solution,  neutral,  or  very  faintly  acid  to  litmus 
paper,  and  having  a  saline,  not  a  strongly  bitter  taste.  A  solution 
containing  one  grain  to  the  fluidounce  will  produce  a  sensation  of 
numbness  in  the  mouth  and  throat  if  a  few  drops  of  it  are  swallowed. 
When  treated  with  Froehde's  reagent  (sulphomolybdic  acid)  the  salt 
Fig.  1.— Cocaine  alkaloid,  commercial  product 
crystallized  from  alcohol.   X  50  diameters. 
should  produce  no  immediate  coloration ;  impure  products  generally 
give  a  reddish  brown  color,  more  or  less  rapidly  fading.  In  a  few 
cases  a  green  color  has  been  observed  to  develop  subsequently. 
The  salt  dissolves  in  less  than  its  own  weight  of  water.  It  is  also 
freely  soluble  in  alcohol,  less  readily  in  absolute  alcohol  and  in  chloro- 
form, and  is  practically  insoluble  in  ether,  in  petroleum  ether  and  in 
^  Authorities  state  that  cocaine  requires  for  solution  704  parts  of  water. 
The  crystalUzed  alkaloid  is  much  less  soluble  than  this,  since  it  crystallizes 
from  a  solution  containing  1:1,500.  It  would  probably  require  of  cold 
water  for  solution  not  less  than  2,000  times  its  weight. 
