ers (Cyanine)._--The blue coloring matter
of flowers we propose to call cyanine. To obtain this substance we treat
the petals of _Centauria cyanus_, _Viola odorata_, or _Iris
pseudacorus_, with boiling alcohol, by which the flowers are
decolorized; and the liquid acquires immediately a fine blue color.

If the coloring matter is allowed to remain some time in contact with
alcohol, it is perceived that the blue of the liquid gradually
disappears, and soon a yellow brown coloration takes its place. The
coloring matter has in this case suffered an actual reduction by the
prolonged action of the alcohol, but it will again assume its original
color when the alcohol is allowed to evaporate in the air. Nevertheless,
the alcohol must not be allowed to remain in contact too long with the
coloring matter, because the alcoholic extract will not then again
assume its blue coloration by the action of oxygen.

The residue remaining from the evaporation of the alcohol is treated
with water, which separates a fatty and resinous substance. The watery
solution which contains the coloring matter is then precipitated by
neutral acetate of lead. The precipitate, which possesses a beautiful
green color, can be washed with plenty of water, and then decomposed
with sulphuretted hydrogen; the coloring matter passes into the watery
solution, which is carefully evaporated in a water-bath; the residue is
again dissolved in absolute alcohol; and lastly, the alcoholic solution
is mixed with ether, which precipitates the cyanine in the form of blue
flocks.

Cyanine is uncrystallizable, soluble in water and alcohol, insoluble in
ether; acids, and acid salts color it immediately red; by alkalies it
is, as known, colored green. Cyanine appears to behave as an acid, at
least it forms with lime, baryta, strontia, oxide of lead, &c., green
compounds insoluble in water.

Bodies absorbing oxygen, as sulphurous acid, phosphorous acid, and
alcohols, decolorize it; under the influence of oxygen its color is
restored.

We must here mention that Moroz has prepared a beautiful blue substance
from _Centauria cyanus_ by treatment with absolute alcohol.

_Rose-red Coloring Matter._--We have employed alcohol to extract the
substance which colors rose-red certain dahlias, roses, poeonias, &c.
For the procuration of this coloring matter the method pursued is
exactly as that for the preparation of cyanine.

By an attentive comparison of the properties of this col