Some flowers which are red, become blue by merely bruising them. Thus,
if the petals of the common corn-poppy be rubbed upon white paper, they
will stain it purple, which may be made green by washing it over with a
strong solution of potash in water. Put poppy petals into very dilute
muriatic acid, and the infusion will be of a florid red colour; by
adding a little chalk, it will become the colour of port wine; and this
tint, by the addition of potash, may be changed to green or yellow.