COLOR OF PLANTS AND FLOWERS. 45 
iron in a low state of oxidation be the coloring substance 
of a flower, it is clear that as soon as the juice of the 
plant becomes more acid, a farther oxidation takes place, 
this would cause a change in color.” 
“T would instance the Lilac. Iron in a low state of oxi- 
dation combined with manganese and carbonic acid, form 
component parts of a mineral called Pearl-spar, which is 
of a brilliant white—it may therefore exist in the same 
state in the white Lilac; and the manganese is often found, 
particularly in the Tiree marble, to be the cause of lilac 
color—as the juices ripen and grow more acid, the iron is 
farther oxidized, the flowers fade, turn of a rusty brown, 
and«finally the seed vessel ripens of a dark brown.” 
That Iron is able to produce almost every variety of 
color we may learn from the fact that the native miner- 
als, Phosphate of iron is of all shades of blue. Sulphate 
and arseniate of iron, are green, brown, yellowish red, 
brownish green. Humboldtine or oxalate of iron is bright 
yellow, etc., ete. 
Manganese is also found of most colors, from the green- 
ish blue*of the Horn Mangan to the rose red of the, Tiree 
marble. 
“The amethyst is supposed to be colored by iron and 
manganese, the emerald by oxide of chrome; the topaz, 
the sapphire and the ruby by iron.” 
“Tt is well known to the florist that over manured soil 
deepens, or spoils, as he calls it, the colors of his tulips and 
other favorites, and that from this deterioration it is diffi- 
cult: to recover them. 
“Strong manure contains a large proportion of alkali, 
and this always deepens and rather deadens many colors, 
particularly of the red and purple tinge, while acids on 
the contrary lighten and enliven them; this consideration 
may be experimentally applied to the subject.” 
A number of years since I sold to a Tulip amateur a bed 
