132. It is important that the words which we use for the different
colors should be well understood, that in using them we use them with
the same meanings. By Red I mean the only positive color which shows
no element either of Yellow or of Blue. It is the color which we often
describe by the word crimson, and we produce it by the mixture of
Rose Madder and Vermilion. By Yellow I mean the only positive color
which shows no element either of Red or Blue. It is the color of the
primrose which may be produced by the pigment Aureolin. By Blue I mean
the only positive color which shows no element either of Yellow or of
Red. Blue is seen in a clear sky after rain and in the pigment Cobalt.
By Orange I mean a positive color showing equal elements of Red and
of Yellow. By Green I mean a positive color showing equal elements of
Yellow and of Blue. By Violet I mean a positive color showing equal
elements of Blue and Red. The character of the intermediates is clearly
indicated by their several names. In each one we see the adjacents in
equal measures. This definition of the colors is only approximate.
It does not pretend to be scientific, but it may help to bring us to
a common understanding. To carry these definitions farther, I should
have to produce examples. This I can do in my class-room, producing
each color according to my idea, exactly. I might reach the same result
approximately by color-printing, but the result would not, probably,
be permanent. The samples produced by hand, for use in the class-room,
can be reproduced from time to time when they no longer answer to the
ideas which they are intended to express. In this treatise I shall
use a terminology instead of colored illustrations which would not be
satisfactory, or, if satisfactory, not so permanently.