round in one fibre (wool) and colour, and the design
in another fibre (cotton) and colour. The number of direct dyes issued
by the various colour manufacturers is so great that it would take a
fairly considerable space to discuss them all.

To obtain good results it is needful that the dyer of union fabrics
should have a thorough knowledge of the dyes he is using, for each dye
makes a rule to itself as regards its power of dyeing wool and
cotton--some go better on to the cotton than on to the wool, and _vice
versa_. Some dye wool best at the boil, others equally well below that
heat; some go on the cotton at a moderate temperature, others require
the dye-bath to be boiling; some will go on to the cotton only, and
appear to ignore the wool.

The presence or absence in the dye-bath of such bodies as carbonate of
soda, Glauber's salt, etc., has a material influence on the degree of
the affinity of the dye-stuff for the two fibres, as will perhaps be
noted hereafter. Again, while some of the dyes produce equal colours on
both fibres, there are others where the tone is different. With all
these peculiarities of the Diamine and other direct dyes the union dyer
must make himself familiar. These dyes are used in neutral baths, that
is, along with the dye-stuff. It is often convenient to use, along with
the direct dyes, some azo or acid dyes, which have the property of
dyeing the wool from neutral baths, many examples of such will be found
in the practical recipes given below. The dyes now under consideration
may be conveniently classed into five groups.

1. Those dyes which dye the cotton and wool from the same bath to the
same shade, or nearly so. Among such are Thioflavine S, Diamine fast
yellow B, Diamine orange B, Diamine rose B D, Diamine reds 4 B, 5 B, 6 B
and 10 B, Diamine fast red F, Diamine Bordeaux B, Diamine brown N,
Diamine browns 3 G, B and G, Diamine blues R W, B X, Diamine blue G,
Diamine greens G and B, Diamine black H W, Diamine dark blue B, Union
blacks B and S, Oxydiamine blacks B, M, D and A, Diamine catechine G,
Union blue B B, Oxyphenine, Chloramine yellow, Alkali yellow R, Chromine
G, Titan scarlet S, Mimosa, Curcumine, Primuline, Auroline, Congo
Corinth B, Thiazole yellow, Columbia yellow, Oxydiamine yellow G G,
Oxydiamine oranges G and R, Diamine orange F, Oxydiamine red S.

2. Dyes which dye the cotton a deeper shade than the wool. The
following belong to this group: Diamine fast yellow A, Diamine o