eam-pipe.]

Plain tubs or vats, such as those shown in figure 10, are used for
dyeing and otherwise treating goods in the cold, or at a lukewarm
heat, when the supply of hot water can be drawn from a separate
boiler. When, however, it is necessary to work at the boil, then the
vat must be fitted with a steam coil. This is best laid along the
bottom in a serpentine form. Above the pipe should be an open
lattice-work bottom, which, while it permits the free circulation of
boiling water in the vat, prevents the material being dyed from coming
in contact with the steam pipe. This is important if uniform shades
are to be dyed, for any excessive heating of any portion of the bath
leads to stains being produced on the material in that part of the
bath. Figure 11 shows a vat fitted with a steam pipe. That portion (p. 043)
of the steam pipe which passes down at the end of the vat is in a
small compartment boxed off from the main body of the vat, so that no
part of the material which is being dyed can come in contact with it.
A closed steam coil will, on the whole, give the best results, as then
no weakening of the dye-liquor can take place through dilution by the
condensation of the steam. Many dye-vats are, however, fitted with
perforated, or as they are called, open steam coils, in which case
there is, perhaps, better circulation of the liquor in the dye-vat,
but as some of the steam must condense there is a little dilution of
it.

DYEING MACHINES.

Dye-tubs and vats, such as those described above, have been largely
superseded by machines in which the handling or working of the
materials being dyed is effected by mechanical means. There have been
a large number of dyeing machines invented, some of these have not
been found to be very practical, and so they have gone out of use.
Space will not admit of a detailed account of every kind of machine,
but only of those which are in constant use in dye-works.

#Dyeing Loose or Raw Wool and Cotton.#--Few machines have been designed
for this purpose, and about the only successful one is

_Delahunty's Dyeing Machine._--This is illustrated in figure 12. It
consists of a drum made of lattice work which can revolve inside an
outer wooden casing. The interior of the revolving drum is fitted with
hooks or fingers, whose action is to keep the material open. One
segment of the drum is made to open so that the loose cotton or wool
to be dyed can be inserted. By suitable gearing the drum