down the reputation of being inspired of the devil and it makes him mad
to have his past thrown up at him in this fashion. If his tactless
admirers would stop saying "it is all a mystery and a miracle to me,
and I cannot understand it" and pay attention to what he is telling them
they would understand it and would find that it is no more of a mystery
or a miracle than anything else. You can make an electrician mad in the
same way by interrupting his explanation of a dynamo by asking: "But you
cannot tell me what electricity really is." The electrician does not
care a rap what electricity "really is"--if there really is any meaning
to that phrase. All he wants to know is what he can do with it.

[Illustration: COMPARISON OF COAL AND ITS DISTILLATION PRODUCTS From
Hesse's "The Industry of the Coal Tar Dyes," _Journal of Industrial and
Engineering Chemistry_, December, 1914]

The tar obtained from the gas plant or the coke plant has now to be
redistilled, giving off the ten "crudes" already mentioned and leaving
in the still sixty-five per cent. of pitch, which may be used for
roofing, paving and the like. The ten primary products or crudes are
then converted into secondary products or "intermediates" by processes
like that for the conversion of benzene into aniline. There are some
three hundred of these intermediates in use and from them are built up
more than three times as many dyes. The year before the war the American
custom house listed 5674 distinct brands of synthetic dyes imported,
chiefly from Germany, but some of these were trade names for the same
product made by different firms or represented by different degrees of
purity or form of preparation. Although the number of possible products
is unlimited and over five thousand dyes are known, yet only about nine
hundred are in use. We can summarize the situation so: