r the purpose of making comparative
tests of dyes or mordanting materials with the object of determining
their strength and value. This is not by any means difficult, nor does
it involve the use of any expensive apparatus, so that a dyer need not
hesitate to set up a small dyeing laboratory for fear of the expense
which it might entail.

In order to carry out the work indicated above there will be required
several pieces of apparatus. First, a small chemical balance, one that
will carry 100 grams in each pan is quite large enough; and such a one,
quite accurate enough for this work, can be bought for 25s. to 30s.,
while if the dyer be too poor even for this, a cheap pair of
apothecaries' scales might be used. It is advisable to procure a set of
gram weights, and to get accustomed to them, which is not a very
difficult task.

In using the balance always put the substance to be weighed on the
left-hand pan, and the weights on the right-hand pan. Never put
chemicals of any kind direct on the pan, but weigh them in a watch
glass, small porcelain basin, or glass beaker, which has first been
weighed, according to the nature of the material which is being
weighed. The sets of weights are always fitted into a block or box, and
every time they are used they should be put back into their proper
place.

The experimenter will find it convenient to provide himself with a few
small porcelain basins, glass beakers, cubic centimetre measures, two or
three 200 c.c. flasks with a mark on the neck, a few pipettes of various
sizes, 10 c.c., 20 c.c., 25 c.c.

The most important feature is the dyeing apparatus. Where only a single
dye test is to be made, a small copper or enamelled iron saucepan, such
as can be bought at any ironmonger's, may be used; this may conveniently
be heated by a gas boiling burner, such as can also be bought at an
ironmonger's or plumber's for 2s.

[Illustration: FIG. 44.--Experimental Dye-bath.]

It is, however, advisable to have means whereby several dyeing
experiments can be made at one time and under precisely the same
conditions, and this cannot be done by using the simple means noted
above.

To be able to make perfectly comparative dyeing experiments it is best
to use porcelain dye-pots--these may be bought from most dealers in
chemical apparatus--and to heat them in a water-bath arrangement.

The simplest arrangement is sketched in Fig. 44; it consists of a copper
bath measuring 15 inches long by 1