be.

_Yellow Coloring Matter._--The simplest experiments show that no analogy
exists between the substance which colors flowers yellow and that of
which we have already spoken. The agents which generate so easily with
cyanine, the rose-red, violet, or green coloration, cannot in any case
impart these colors to the yellow substance obtained from flowers.

By the examination of the various yellow-colored flowers, we have
ascertained that they owe their coloration to two substances, which
differ from one another in their properties, and appear not to be
derived from the same independent principle. One is completely insoluble
in water, which we have termed xanthine, a name which Runge has given
to a yellow matter from madder. As this name has not been accepted in
science, we have employed it to denote one of the coloring matters of
yellow flowers. The other substance is very soluble in water, and is by
us termed xantheine.

_Xanthine, or the Yellow Coloring Matter insoluble in water._--We have
prepared this coloring matter from many yellow flowers, but chiefly from
_Helianthus annuus_.

To obtain it we treat the flowers with boiling absolute alcohol, which
dissolves the coloring matter in the heat, and by cooling almost
completely allows it again to precipitate. The yellow deposit which is
obtained in this way, is not pure xanthine, as it contains a rather
considerable quantity of oil. To separate this oil we have recourse to a
moderate saponification; thus, we heat the yellow precipitate with a
small quantity of alkali to saponify the fatty body mixed with the
xanthine, which even contains the xanthine dissolved. As the coloring
matter is soluble in the soap solution, we do not treat the mass with
water, but decompose it with an acid which isolates the xanthine and the
fatty acids resulting from the saponification. This precipitate we treat
with cold alcohol, which leaves behind the fatty acids, and dissolves
the xanthine. This substance is a fine yellow color, insoluble in water,
but soluble in alcohol and ether, which are thereby colored golden
yellow. It appears to be uncrystallizable, and possesses the general
properties of resins.

Xanthine, in combination with cyanine, modified by the various juices of
plants, communicates in variable proportions orange-yellow, scarlet-red,
and red colors to flowers.

_Xantheine, or the Coloring Matter soluble in water._--By the
preparation of the substance which colors yellow