42  Eldrin,  a  New  Plant  Constituent.      f  Am.  jour.  Pharm. 
into  the  water  a  small  amount  of  this  material.  Note  that  it  set- 
tles to  the  bottom.  It  is  perfectly  insoluble.  One  grain  shaken 
with  a  gallon  of  water  apparently  disappears,  but  if  let  stand  until 
the  next  day,  behold,  it  is  all  at  the  bottom.  I  now  shake  the  mix- 
ture, and  pour  half  of  it  into  another  cylinder,  then  add  a  little  am- 
monia waer — note  the  change  in  color,  to  deep  yellow.  A  very 
delicate  reagent  is  it  for  an  alkali.  Let  us  now  make  both  liquids 
yellow.  Into  one  I  pour  diluted  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  I 
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 
concerning  the  theories  I  now  hold.  I  may  be  right  and  I  may  be 
wrong.  We  can  see  this  color  change  and  we  know  that  the  petals 
hold  organic  acid.  What  of  it?  I  don't  claim  that  anything  I  have 
brought  is  new ;  quite  the  contrary.  So  far  as  I  know,  this  experi- 
ment 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  the  material  could  not  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  sul- 
phuric 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. 
