476  Alcohol  in  Titration  of  Alkaloids.     { timber %?/ 
to  say  that  it  was  the  product  of  a  well-known,  reliable  American 
manufacturer.  The  alcohol  used  was  such  as  is  usually  sold  to 
pharmacists  by  the  jobber  as  prime  cologne  spirit. 
If,  then,  alcohol  plays  so  important  a  part  in  color  reactions,  it  is 
more  than  likely  that  its  presence  will  influence  more  or  less  the 
results  obtained  in  the  titration  of  alkaloidal  residues,  and  hence  it 
should  be  rigidly  excluded  in  all  such  work  if  accuracy  is  desired. 
It  may  be  employed  to  bring  the  impure  (often  resinous)  residue 
into  solution,  so  that  the  decinormal  acid  can  dissolve  the  alkaloid 
more  readily,  but  should  invariably  be  dissipated  by  the  application 
of  heat  before  titration  of  the  acid  solution  is  undertaken. 
To  show  the  effect  of  alcohol  on  the  valuation  of  alkaloids,  and  to 
point  out  more  forcibly  the  necessity  for  the  absence  of  this  solvent 
in  such  operations,  four  alkaloids — morphine,  cocaine,  atropine  and 
strychnine — all  of  American  manufacture,  were  assayed  volumetric- 
ally  both  in  aqueous  and  dilute  alcohol  solution.  Quinine  and  cin- 
chonine  cannot  be  determined  volumetrically  like  the  other  alkaloids 
above  mentioned,  because  when  in  acid  solution,  prepared  exactly 
like  the  others,  both  give  an  alkaline  color  indication  with  cochineal 
and  tropaeolin ;  with  haematoxylin  and  Brazil  wood,  although  the 
reaction  at  first  is  acid,  an  alkaline  reaction  occurs  before  the  excess 
of  acid  is  neutralized,  and  hence  results  entirely  too  high  are 
obtained. 
The  solutions  used  in  making  the  following  determinations  were 
so  prepared  that  100  c.c.  of  finished  product  contained  O  500  gramme 
of  alkaloid  and  20  c.c.  of  decinormal  acid;  10  c.c.  of  this  solution 
were  used  for  each  titration,  centinormal  alkali  solution  being  used 
to  determine  the  excess  of  acid.  The  equivalent  of  1  c.c.  T^  KOH 
solution  in  ^  H2S04  was  determined  for  each  indicator,  so  that  accu- 
rate calculation  as  to  percentage  could  be  made.  The  proportion 
of  pure  alkaloid  determined  in  both  the  water  and  the  dilute  alcohol 
solutions  is  given  opposite  each  indicator  for  the  sake  of  ready  com- 
parison, the  quantity  of  indicator  used  having  been  the  same  as  stated 
in  the  experiments  with  plain  solvents,  mentioned  above.  Two  extra 
determinations  were  made  in  the  case  of  each  alkaloid,  with  haema- 
toxylin and  tropaeolin  OO,  after  addition  of  5  c.c.  alcohol  to  the 
dilute  alcohol  solution ;  this  was  done  for  the  purpose  of  showing 
the  effect  of  a  larger  proportion  of  alcohol,  whereby  the  detrimental 
influence  of  the  latter  liquid  is  emphasized. 
