Am, 
So 
j*}  Coca  Leaf,  and  Fluid  Extract  of  Coca. 
573 
Methods. 
Per  cent,  of 
Alkaloids, 
Gravimetrically. 
Per  cent,  of 
Alkaloids, 
Volumetrically. 
Squibb1 
075 
0*64 
0'67 
0-485 
0-58 
0-481 
0516 
0-34 
v.  d  Marck2    .  . 
Pfeiffer3    .  .  .  . 
Lyons4  (general) 
Lyons4  (ether) 
Lyons4  (benzine) 
0-521 
Keller6  (4  hours  maceration)  .  . 
Keller  (24  hours  maceration)  . 
0-56 
062 
0-532 
0-563 
In  order  that  a  method  may  be  of  the  greatest  practical  value,  it 
must  be  easily  executed,  extract  the  largest  percentage  of  alkaloids 
possible  in  a  comparatively  short  time,  and  at  the  same  time  be 
neat.  Dr.  Squibb's  method  extracts  the  largest  per  cent,  of  alka- 
loids, but  requires  too  much  time.  Marck's  method  requires 
too  much  time,  and  yields  unsatisfactory  results,  volumetric- 
ally.  Pfeiffer's  process  is  adapted  for  volumetric  work  only. 
While  this  method  gives  fairly  satisfactory  results,  it  is  inelegant, 
and  great  care  must  be  exercised  to  remove  all  of  the  caustic  soda. 
Lyons'  general  method  of  assay,  and  the  one  in  which  ether  is  the 
principal  solvent,  are  quite  satisfactory.  The  benzine  method  is 
inaccurate.  The  method,  as  modified  by  Messrs.  Caspari  and 
Dohme,  yields  good  results.  The  Schweissinger-Sarnow  method,  as 
modified  by  Keller,  yields  the  most  satisfactory  results.  Several 
other  methods  were  tried,  but  were  never  finished,  on  account  of  the 
stubborn  emulsions  formed. 
In  concluding  this  part  of  the  work,  it  is  only  necessary  to  say 
that  Keller's  method  has  proven  itself  superior  to  Lyons'  method 
in  extracting  a  slightly  larger  per  cent,  of  alkaloids,  and  is  less 
prone  to  emulsify. 
Mr.  Dohme  presented  a  paper,  at  the  last  meeting  of  the  Ameri- 
1 1885,  Ephemeris,  2,  784. 
2 1889,  Nederl.  Tydschr.  v.  Pharm.  Chem.,  April  ;  Analyst,  14,  115. 
:1 1887,  Chem.  Ztg.,  11,  783  and  818. 
4  Pharmaceutical  Assay,  \  29-36,  154-157. 
5 1893,  Am.  J.  Pharm.,  65,  478. 
"1892,  Schweiz.  Wochenschr.  f.  Chem.  u.  Pharm.,  30,501  ;  Am.  J.  Pharm., 
6.".,  78. 
