hrough which they are passed; at any rate a card
does not last as long when working dyed cotton or wool as when used on
undyed cotton or wool fibres. Yet for the production of certain fancy
yarns for weaving some special classes of fabrics, it is desirable to
dye the cotton or wool before it is spun into thread. The best plan is
undoubtedly to dye the fibre after it has been carded and partly spun
into what is known as slubbing or sliver. All the impurities have been
removed, the cotton fibres are laid, straight, and so it becomes much
easier to dye. On the other hand, as it is necessary to keep the sliver
or slubbing straight and level, no working about in the dye-liquors can
be allowed to take place, and so such must be dyed in specially
constructed machines, and one of the best of these is the Obermaier
dyeing machine which is illustrated in Fig. 10. The Obermaier apparatus
consists of a dye vat A. In this is placed a cage consisting of an inner
perforated metal cylinder C, and an outer perforated metal cylinder D,
between these two is placed the material to be dyed. C is in contact
with the suction end of a centrifugal pump P, the delivery end of which
discharges into the dye-vat A. The working of the machine is as follows:
The slubbing or sliver is placed in the space between C and D rather
tightly so that it will not move about. Then the inner cage is placed in
the dye-vat as shown. The vat is filled with the dye-liquor which can be
heated up by a steam pipe. The pump is set in motion, the dye liquor is
drawn from A to C, and, in so doing, passes through the material packed
in B and dyes it. The circulation of the liquor is carried on as long as
experience shows to be necessary. The dye-liquor is run off, hot water
is run in to wash the dyed material, and the pump is kept running for
some time to ensure thorough rinsing; then the water is run off, and by
keeping the pump running and air going through a certain amount of
drying can be effected. This machine works very well, and, with a little
experience, constant results can be obtained. The slubbing or sliver may
be scoured, bleached, rinsed, dyed, washed, soaped, or otherwise treated
without removing it from the machine, which is a most decided advantage.

[Illustration: FIG. 11.--Holliday's Yarn-dyeing Machine.]

=Holliday's Yarn-dyeing Machine.=--In Fig. 11 is given an illustration
of a machine for dyeing yarn in the hank form made by Messrs. Read
Holliday & So