ssess a special
affinity for vegetable fibre, and their introduction has exerted a great
influence upon the art of cotton-dyeing. We shall have to return to these
cotton-dyes again shortly.

Before leaving this branch of the subject, the following scheme is
presented to show the relationships and inter-relationships of the
products thus far dealt with in the present chapter--

Tar
|
---------------------------------------------------------
| |
Light Oil Carbolic Oil
/ \ /-> Benzal Chloride |
/ \ / | \ |
/ \ / | Benzaldehyde |
/ \ / Cinnamic acid | |
Benzene Toluene | Nitrobenzaldehyde |
| | Nitrocinnamic acid (+ acetone) |
| | | / |
| | | / |-----------|
Nitrobenzene Nitrotoluene Propiolic acid / | |
| | \ | / Phenols Naphthalene
| | \ | / | \
| | \ | / | \
| | \ | / | ->Cresols
Azobenzene Azotoluene \ Indigo<--/ Phenol |
| | Stilbene- | Victoria
| | derivative <------------------- yellow
| | (Diazotised)\ | \
Benzidine Tolidine Salicylic Picric Corallin
\ / acid acid & Aurin
(Diazotised) \/
--------------------------------

The existence of naphthalene in coal-tar was made known in 1820 by Garden,
who gave it this name because the oils obtained from the tar by
distillation went under the general designation of naphtha. The greater
portion of the hydrocarbon is contained in the carbolic oil, and is
separated and purified in the manner described. A further quantity of
impure naphthalene separates out from the next fraction--the creosote oil,
and t