nly determined
by the price of the raw material from which it is manufactured, the
working expenses, and the profit desired by the manufacturer. Neither
must we suppose that facility of application necessarily interferes
with its fastness to light, for some of our fastest coal tar colors on
wool, e.g., diamine fast red, tartrazin, etc., are applied in the
simplest possible manner. On the other hand, the intensity or depth of
a color has considerable influence on its fastness. Dark full shades
invariably appear faster than pale ones produced from the same
coloring matter, simply because of the larger body of pigment present.
A pale shade of even a very fast color like indigo will fade with
comparative rapidity. The fugitive character of many of the coal tar
colors is, in my opinion, rendered more marked, because, owing to
their intense coloring power, there is often such an infinitesimal
amount of coloring matter on the dyed fiber. Hence it is that in the
Gobelin tapestries pale shades on wool are frequently obtained by the
use of more or less unchangeable metallic oxides and other mineral
colors, to the exclusion of even fast vegetable dyes.

It is interesting to examine what is the action of light upon compound
colors. Is a fugitive color rendered faster by being applied along
with a fast color?

My own opinion, based upon general observation, is that it is not, and
that when light acts upon a compound color the unstable color fades,
while the stable color remains behind. A woaded color, for example, is
only fast in respect of the vat indigo which it contains, and yet how
frequent is the custom to unite with the indigo such dyes as barwood,
orchil, and indigo-carmine, the fugitive character of which I have
pointed out.

Having thus rapidly surveyed these numerous coal tar colors, both in
their dyed and exposed conditions, I again ask why are they so
generally regarded as altogether fugitive?

First, because we have, especially among these "direct dyes," a very
large number which are undoubtedly very fugitive.

Moreover, all the earlier coal tar dyes--mauve, magenta, Nicholson
blue, etc., belonged to a class which, even up to the present time,
has only furnished us with fugitive colors. They were indeed prepared
from aniline, and it appears to me that the defects of these early
aniline colors, as well as their designation, have been handed down to
their successors without due discrimination, so that in the popular