Am.  Jour.  Pharm. 
October.  1S95. 
}    Acidimetric  Estimation  of  Alkaloids. 
503 
My  associate,  Mr. -La  Wall,  took  up  a  portion  of  the  work,  which 
he  executed  independently,  using,  however,  the  same  solutions  and 
apparatus  that  the  writer  employed.  The  above  and  all  subsequent 
results  are  the  average  of  duplicate,  triplicate  or  more  titrations. 
The  titration  of  pure  alkaloids,  as  found  in  the  market,  was  next 
undertaken.  With  quinine  and  codeine  the  following  method  was 
used  :  two  grammes  of  the  alkaloid  were  placed  into  the  cylinder, 
dissolved  in  alcohol  and  diluted  up  to  100  c.c.  with  alcohol.  To  10 
c.c.  of  this  solution  and  the  requisite  quantity  of  indicator,  contained 
in  a  suitable  beaker,  the  decinormal  acid  solution  was  added  to  slight 
excess,  agitated,  allowed  to  stand  a  few  minutes,  the  sides  of  the 
beaker  well  washed  down  with  distilled  water,  adding  about  40  c.c, 
and  the  excess  of  acid  titrated  back  with  the  centinormal  alkaline 
solution. 
With  alkaloids  not  freely  soluble  in  alcohol,  the  following  proce- 
dure was  adopted:  two  grammes  of  the  alkaloid  were  placed  into 
a  200  c.c.  beaker,  75  c.c.  of  decinormal  acid  added,  the  contents  of 
the  beaker  warmed  on  a  water  bath  and  occasionally  agitated  until 
the  alkaloid  was  dissolved.  The  beaker  and  contents  were  then 
cooled,  the  contents  transferred  to  a  100  c.c.  cylinder,  the  beaker 
carefully  rinsed  with  several  successive  portions  of  water,  transferred 
to  the  100  c.c.  cylinder,  and  finally  made  up  to  100  c.c.  with  water. 
Each  10  c.c.  contained  0'2  grammes  of  alkaloid  and  7-5  c.c.  of  deci- 
normal acid  solution.  After  adding  the  requisite  amount  of  indi- 
cator to  10  c.c.  of  the  alkaloidal  solution,  and  diluting  up  to  about 
50  c.c.  the  excess  of  acid  was  carefully  retitrated.  Two  or  more 
titrations  were  made  in  every  case,  with  the  same  solution  and  indi- 
cator, by  adding  to  the  solution  just  finished  another  portion  of 
decinormal  acid  solution  and  retitrating  with  the  centinormal  alka- 
line solution,  taking  finally  the  average  reading. 
The  above  methods  of  titration  and  preparation  of  solutions  were 
Indicators. 
Quinine. 
La  Wall. 
Quinine. 
Kebler. 
Strychnine. 
Kebler. 
Morphine. 
Kebler. 
Codeine. 
Kebler. 
Brazil  wood  .  . 
Cochineal    .  . 
Haematoxylin 
Litmus  .  .  .  . 
Methyl  orange 
99-90 
105-56 
99'Si 
;orSo 
99"36 
IOV20 
100*03 
103-  54 
104-  2 1 
9S-93 
99*oS 
9S-I7 
9S-93 
100-59 
95  75 
97-09 
95*90 
96-3S 
9S*n 
