656  Titration  of  Certain  Alkaloids.  |AmseJp°tur'i92iarm' 
After  preserving  and  mounting  as  described,  the  coloring  matter 
from  several  flowers  of  the  same  species  was  extracted  with  abso- 
lute alcohol,  and  the  liquid  thus  obtained  was  used  to  paint  the  speci- 
men intended  for  the  herbarium.  In  this  manner  an  example  of 
Iris  pseudacorus  has  the  appearance  of  having  actually  retained 
its  yellow  color. 
In  conclusion,  we  would  commend  this  new  method  to  those 
who  have  suffered  many  disappointments  in  endeavoring  to  make 
a  satisfactory  herbarium  by  the  old  system  of  continued  pressing. 
The  process  here  explained  has  been  tried  and  proved,  and  we  are 
able  to  claim  for  it  that  it  not  only  gives  more  gratifying  results,  but 
that  it  is  also  easier  to  manipulate. 
THE  TITRATION  OF  CERTAIN  ALKALOIDS  * 
By  Norman  Evers,  B.  Sc.,  F.  I.  C. 
In  examining  the  literature  of  analytical  chemistry  in  the  light 
of  modern  development  of  the  theory  of  titrations  one  is  struck  by 
the  haphazard  way  in  which  indicators  are  recommended  for  titra- 
tions. Most  frequently  indicators  appear  to  have  been  chosen  on  ac- 
count of  the  sharpness  of  the  end-point  rather  than  on  account  of 
suitability  on  theoretical  grounds  for  the  titration  in  question.  Fur- 
ther, the  indicators  used  are  chiefly  confined  to  methyl  orange,  phe- 
nolphthalein,  litmus,  and  cochineal  no  one  of  which,  with  the  excep- 
tion of  phenolphthalein,  can  be  regarded  as  a  good  indicator  when 
compared  with  the  new  and  brilliant  indicators  which  are  now 
available.  .  Probably  the  chief  reason  why  these  new  indicators  are 
not  in  more  common  use  is  the  absence  of  any  data  as  to  the  titra- 
tions to  which  they  are  applicable. 
THEORETICAL  CONSIDERATIONS. 
In  a  theoretically  perfect  titration  of  a  weak  base,  such  as 
morphine,  we  should  run  in  standard  hydrochloric  acid  until  we  had 
in  our  solution  nothing  but  pure  morphine  hydrochloride.  The 
means  by  which  we  determine  when  the  morphine  is  in  the  state 
of  hydrochloride  is  by  adding  an  indicator.  Now  all  indicators  change, 
*From  Pharm.  Jour,  and  Pharm.,  June  18,  1921. 
