866 
Plant  Constitu&nts. 
(  Am.  Jour.  Pharm. 
I      Dec,  1921. 
water — note  the  change  in  color  to  deep  yellow.  A  very  delicate  re- 
agent is  it  for  an  alkali.  Let  us  now  make  both  liquids  yellow.  Into 
one  I  pour  dilute  sulphuric  acid,  in  excess,  to  destroy  the  ammonia. 
The  liquid  becomes  colorless. 
Now  the  question  came  to  me,  "Why  is  the  white  flower  white 
when  it  has  the  yellow  material  in  it  in  such  quantity?"  Then  1 
figured  to  myself,  it  must  be  because  the  white  petals  carry  also  an 
acid  which  in  contact  with  the  yellow  material  makes  it  white.  In 
other  words,  would  the  white  flower  be  yellow  if  there  was  an  alkali 
in  the  petal  instead  of  an  acid?  Crushing  the  flower  in  a  mortar  with 
a  little  distilled  water  gave  a  sharp  acid  reaction.  Blue  litmus  turned 
red  at  once.   The  acid  was  present. 
The  question  arises,  What  is  the  use  of  this  thing  in  nature? 
I  think  I  comprehend  the  subject,  but  it  is  too  great  to  try  to  bring 
before  you  today. 
I  am  going  to  ask  you  to  be  charitable  in  what  I  have  said  con- 
cerning the  theories  I  now  hold.  I  may  be  right  and  I  may  be 
wrong.  Wre  can  see  this  color  change  and  we  know  that  the  petals 
hold  organic  acid.  WThat  of  it?  I  don't  claim  that  anything  I  have 
brought  is  new ;  quite  the  contrary.  So  far  as  I  know,  this  ex- 
periment has  not  been  made.  In  some  literature  unbeknown  to  me 
it  may  be  explained.  It  doesn't  matter  whether  it  is  new  or  old — it 
is  a  phase  in  plant  economy  that  is  a  fact,  and  may  be  of  service 
other  than  as  a  medicine. 
I  asked  myself,  Why  could  not  the  material  be  used  to  make  a 
test  paper  ?  Why  would  not  paper  saturated  with  a  solution  of  this 
material  turn  yellow  with  alkali  and  colorless  with  acid?  I  tried 
it  and  it  worked.  There  is  a  shade  between  red  and  blue  litmus  which 
makes  it  difficult  sometimes  to  quite  determine  the  end  reaction. 
There  is  no  intermediate  shade  with  this. 
For  example,  let  us  now  pour  into  these  tumblers  some  water, 
and  into  the  one  put  some  ammonia  and  in  the  other  dilute  sulphuric 
acid.  The  paper  I  hold  in  my  hand  has  been  saturated  with  a  weak 
solution  of  this  material  and  dried.  I  dip  it  into  the  acid.  See,  it  is 
colorless.    Now  I  dip  it  into  the  ammonia ;  it  instantly  turns  yellow. 
You  ask  the  name  of  this  material.  I  call  it  Eldrin.  But  it 
may  have  been  long  known  elsewhere  and  recorded  under  a  differ- 
ent name  or  different  terms. 
