COLORING  MATTERS  OF  FLOWERS. 
545 
OBSERVATIONS  ON  THE  COLORING  MATTERS  OF  FLOWERS. 
By  E.  Filhol. 
White  Flowers. — If  flowers  of  Viburnum  opulus,  Philadelphus 
coronaria,  Chrysanthemum  vulgare,  white  roses,  and  a  number  of 
other  flowers,  be  exposed  for  a  few  moments  to  the  action  of  am- 
monia, they  acquire  a  yellow  tinge  of  greater  or  less  intensity, 
which  remains  for  a  considerable  time.  Flowers  of  Viburnum 
opulus  by  this  treatment  acquire  a  yellow  color  as  fine  as  that  of 
Cytisus  laburnum.  The  matter  which  thus  becomes  yellow  under 
the  influence  of  alkalies  appears  to  be  present  in  all  white  flowers; 
some  flowers  contain  only  a  small  quantity  of  it,  but  these  are 
rare. 
In  variegated  flowers  of  which  the  corolla  is  partially  white, 
these  portions  usually  acquire  a  fine  yellow  tint  under  the  influence 
of  ammonia.  The  stamina,  the  pistils,  and  in  general  all  the 
white  parts  of  flowers,  act  in  the  same  manner.  The  leaves  them- 
selves become  yellow  when  they  are  accidentally  deprived  of 
chlorophylle.  I  ascertained  this  fact  with  a  plant  of  Co?ivallaria 
polygonatum,  of  which  the  leaves  presented  alternate  green  and 
white  bands.  The  latter  became  bright  yellow  from  the  action  of 
ammonia,  exactly  like  flowers.  The  tissue  of  some  fruits  also  be- 
comes yellow,  although  less  distinctly,  under  the  influence  of  alka- 
lies. 
The  most  convenient  mode  of  converting  a  white  flower  into  a 
yellow  one  is  to  introduce  it  into  a  wide-mouthed  flask  containing 
a  little  liquid  ammonia,  and  to  expose  it  to  the  action  of  the  alka- 
line vapor.  The  change  then  takes  place  very  rapidly.  When 
the  greatest  part  of  the  flower  has  become  yellow,  it  may  be  taken 
out  of  the  flask  and  exposed  to  the  air,  when  the  parts  which  still 
remained  white  will  gradually  charge  until  the  flower  acquires  a 
uniform  tint.  The  flower  may  also  be  dipped  into  water,  alcohol 
or  ether,  mixed  with  a  little  ammonia.  The  latter  fluids  should 
be  preferred  when  the  flower  is  covered  with  a  fatty  coating,  which 
would  prevent  their  being  moistened  by  a  watery  fluid.  If  a  white 
flower  that  has  been  rendered  yellow  be  dipped  into  acidulated 
water,  it  gradually  recovers  its  white  color. 
These  experiments  remind  one  that  when  dyers  wish  to  employ 
the  color  of  woad  in  dyeing,  they  add  a  little  carbonate  of  soda  to 
35 
