r advisable in a work of this kind to pursue
the many chemical reactions, which, from the various acids and bases,
result ultimately in the many shades and gradations of colour which are
to be seen in dress and other fabrics. Many of them, beautiful in the
extreme, are the outcome of much careful and well-planned study, and to
print here the complicated chemical formulae which show the great changes
taking place in compounds of complex molecules, or to mention even the
names of these many-syllabled compounds, would be to destroy the purpose
of this little book. The Rosanilines, the Indulines, and Safranines; the
Oxazines, the Thionines: the Phenol and Azo dyes are all substances which
are of greater interest to the chemical students and to the colour
manufacturer than to the ordinary reader. Many of the names of the bases
of various dyes are unknown outside the chemical dyeworks, although each
and all have complicated; reactions of their own. In the reds are
rosanilines, toluidine xylidine, &c.; in the blues--phenyl-rosanilines,
diphenylamine, toluidine, aldehyde, &c.; violets--rosaniline, mauve,
phenyl, ethyl, methyl, &c.; greens--iodine, aniline, leucaniline,
chrysotoluidine, aldehyde, toluidine, methyl-anilinine, &c.; yellows and
orange--leucaniline, phenylamine, &c.; browns--chrysotoluidine, &c.;
blacks--aniline, toluidine, &c.

To take the rosanilines as an instance of the rest.

Aniline red, magenta, azaleine, rubine, solferino, fuchsine, chryaline,
roseine, erythrobenzine, and others, are colouring matters in this group
which are salts of rosaniline, and which are all recognised in commerce.

The base rosaniline is known chemically by the formula C_{20}H_{l9}N_{3},
and is prepared by heating a mixture of magenta aniline, toluidine, and
pseudotoluidine, with arsenic acid and other oxidising agents. It is
important that water should be used in such quantities as to prevent the
solution of arsenic acid from depositing crystals on cooling. Unless
carefully crystallised rosaniline will contain a slight proportion of the
arseniate, and when articles of clothing are dyed with the salt, it is
likely to produce an inflammatory condition of skin, when worn. Some
years ago there was a great outcry against hose and other articles dyed
with aniline dyes, owing to the bad effects which were produced, and this
has no doubt proved very prejudicial to aniline dyes as a whole.

Again, the base known as mauve, or mauveine, has a