Am"octuyisP93arm'}  Titration  as  a  Means  of  Assaying  Drugs,  475 
we  know  to  be  absolutely  correct,  it  is  our  opinion  that  the  method 
of  titration  with  volumetric  acid  solution  is  by  far  the  most  reliable 
method  we  possess  to-day  for  assaying  alkaloidal  drugs.  In  all 
cases  we  used  the  fluid  extracts  of  the  drugs  examined.  Some 
trouble  was  experienced  in  getting  an  indicator  that  would  give  a 
sharp  end  reaction  in  case  of  slightly-colored  solutions,  but  a  decoc- 
tion of  Brazil  wood  containing  a  little  alcohol  was  found  to  answer 
all  purposes.    Our  plan  of  procedure  was  as  follows  : 
Four  separate  and  distinct  methods  of  assay  were  undertaken  in 
case  of  each  fluid  extract  examined,  and  the  amount  of  error  in  each 
determined  by  means  of  titration  with  volumetric  acid  solution. 
The  methods  adopted  were  those  of  Lyons,  Lloyd,  Beckurts  and 
Thompson.  By  employing  these,  as  prescribed  in  their  method,  we 
obtained  the  usual  gravimetric  results  given  in  the  columns  below, 
headed  "  gravimetric."  The  residues  were  then  dissolved  in  a  known 
quantity  of  decinormal  hydrochloric  acid  dropped  into  the  beaker 
from  a  graduated  burette,  using  a  little  heat  by  placing  it  on  a  water- 
bath,  if  the  alkaloids  resisted  solution  due  to  the  presence  of  resin, 
gum  or  other  impurities.  After  cooling,  the  indicator  was  added, 
about  10  or  12  drops,  and  the  excess  of  acid  determined  by  means 
of  a  volumetric  alkali  solution,  whose  relation  to  the  decinormal  acid 
solution  we  know ;  the  alkali  solution  being  added  until  the  solution 
became  cardinal  to  purplish  red  in  color,  indicating  an  excess  of 
alkali.  The  number  of  cubic  centimeters  of  alkali  solution  used 
were  then,  after  being  converted  into  their  equivalent  of  decinormal 
acid  solution,  subtracted  from  the  original  amount  of  decinormal 
acid  solution  added.  This  gave  the  amount  of  decinormal  acid  that 
had  been  used  to  neutralize  the  alkaloids  present  in  order  to  form 
with  them  their  hydrochlorides.  We  know  that  for  every  36-37 
grammes  of  hydrochloric  acid  used  there  must  be  present  an  amount 
of  alkaloid  equivalent  in  grammes  to  its  molecular  weight,  provided 
the  alkaloid  is  a  monacid  base.  If  it  is  a  diacid  base,  as  in  case  of 
ipecac,  where  emetine  is  known  to  be  diacid,  then  36-37  grammes  of 
hydrochloric  acid  will  neutralize,  i.e.,  indicate  only  one -half  of  the 
molecular  weight,  in  grammes,  of  the  alkaloid.  To  show  the  exact 
method  employed  in  calculating  the  results  recorded  below,  we  will 
take  the  cases  of  belladonna  root,  nux  vomica  and  ipecac  root. 
The  molecular  weights  of  the  three  mydriatic  alkaloids  contained  in 
belladonna  root  being  all  alike,  we  do  not  hesitate  to  represent  it  by 
