rns are hung
on trucks which can be run in and out of the chamber for filling and
emptying.

_Piece Goods._--The most convenient manner of drying piece goods is to
employ the steam cylinder drying machine, such as is shown in Fig. 43.
This consists of a number of hollow tin or copper cylinders which can be
heated by steam passing in through the axles of the cylinders, which are
made hollow on purpose. The cloth to be dried passes round these
cylinders, which revolve while the cloth passes. They work very
effectually. The cylinders are arranged sometimes, as in the drawing,
vertically; at other times horizontally.

CHAPTER VIII

TESTING OF THE COLOUR OF DYED FABRICS.

It is frequently desirable that dyers should be able to ascertain with
some degree of accuracy what dyes have been used to dye any particular
samples of dyed cloth that has been offered to them to match. In these
days of the thousand and one different dyes that are known it is by no
means an easy thing to do; and when, as is most often the case, two or
three dye-stuffs have been used in the production of a shade, the
difficulty is materially increased.

The only available method is to try the effect of various acid and
alkaline reagents on the sample, noting whether any change of colour
occurs, and judging accordingly. It would be a good thing for dyers to
accustom themselves to test the dyeings they do, and so accumulate a
fund of practical experience which will stand them in good stead
whenever they have occasion to examine a dyed pattern of unknown origin.

The limits of this book does not permit of there being given a series of
elaborate tables showing the action of various chemical reagents on
fabrics dyed with various colours; and such, indeed, serve very little
purpose, for it is most difficult to describe the minor differences
which often serve to distinguish one colour from another. Instead of
doing so, we will point out in some detail the methods of carrying out
the various tests, and advise all dyers to carry these out for
themselves on samples dyed with known colours, and when they have an
unknown colour to test to make tests comparatively with known colours
that they think are likely to have been used in the production of the
dyed fabric they are testing.

One very common method is to spot the fabric, that is, to put a drop of
the reagent on it, usually with the end of the stopper of the reagent
bottle, and to observe the colou