'^  D^.^isS^'''"  }      ^^^^  Coloring  Matter  of  Flowers, 
599 
It  is  quite  sensitive  to  the  mineral  acids  even  in  dilute  solutions, 
but  I  found  it  necessary  to  have  rather  strong  solutions  of  the  vegeta- 
ble acids  (acetic  acid  excepted)  in  order  to  get  the  color  reaction. 
With  the  alkalies  I  experienced  no  trouble  as  it  invariably  turned 
green. 
In  order  to  form  an  approximate  idea  as  to  the  strength  of  the  solu- 
tion necessary  to  make  a  good  test  paper,  I  procured  a  quantity  of 
the  flowers  (which  was  necessarily  small  owing  to  the  lateness  of  the 
season),  took  the  purple  parts  of  fifteen  flowers,  which  weighed  450 
grains,  added  two  ounces  of  hot  water,  allowed  it  to  stand  ten 
minutes;  then  filtered  it  and  evaporated  to  one-half  ounce.  This 
I  found  sufficiently  strong  for  a  good  test  paper. 
On  preparing  red  and  green  paper  in  the  same  manner  as  litmus 
paper  is  prepared,  I  found  that  the  color  is  not  permanent,  but,  in  the 
course  of  a  few  days,  changed  back  again  to  the  original  blue. 
Another  strange  feature  I  noticed,  upon  drying  a  portion  of  the 
flowers  to  ascertain  the  amount  of  moisture  present,  that  the  colored 
portion  upon  being  thoroughly  dried  changed  to  a  brown  and  there- 
fore did  not  answer  for  testing.  This  shows  that  only  fresh  flowers 
could  be  used. 
It  is  not  likely  that  this  coloring  matter  will  ever  answer  for  gen- 
eral use  as  well  as  litmus;  but  it  would  be  interesting  to  know 
whether  it  might  not  be  used  in  some  cases  where  litmus  would  not 
answer  the  same  purpose. 
NOTE   ON  THE  BLUE  COLORING  MATTER  OF 
FLOWERS. 
By  the  Editor. 
Read  at  the  Pharmaceutical  Meeting,  November  20th. 
Mr.  Greenawalt's  observations  with  the  flowers  of  Iris  versicolor, 
recorded  in  the  preceding  paper,  show  that  the  coloring  matter  of 
these  flowers  agrees  in  behavior  with  that  of  other  blue  flowers.  The 
principles  to  which  flowers  owe  their  characteristic  colors  do  not 
appear  to  have  been  the  subject  of  recent  researches,  and  the  results 
obtained  by  older  investigations  have  been  more  or  less  forgotten,  and 
are  not  referred  to  in  many  chemical  text-books  in  which  some  infor- 
mation on  such  an  interesting  subject  would  naturally  be  sought  for; 
