are clean and free from any size or grease. A little
soda or soap will facilitate the cleansing process.

In carrying out a dyeing test the dye-pot should be filled with the
water required, using as little as can be consistent with the dye swatch
being handled comfortably therein, then there is added the required
mordants, chemicals, dyes, etc., according to the character of the work
which is being done.

Of such chemicals as soda, caustic soda, sodium sulphate (Glauber's
salt), tartar, bichromate of potash, it will be found convenient to
prepare stock solutions of known strength, say 50 grams per litre, and
then by means of a pipette any required quantity can be conveniently
added. The same plan might be followed in the case of dyes which are
constantly in use, in this case, 5 grams per litre will be found strong
enough.

Supposing it is desired to make a test of a sample of direct red, using
the following proportions: 2 per cent. dye-stuff, 3 per cent. soda, 15
per cent. Glauber's salt, and the weight of the swatch which is being
used is 5 grams. The following calculations are to be made to give the
quantities of the ingredients required.

For the dye-stuff:--

5 (weight of swatch) multiplied by 2 (per cent. of dye) and divided by
100 equals--

5 x 2
------- = 0.1 gram dye
100

For the soda we have similarly:--

5 x 3
------- = 0.15 gram soda.
100

For the Glauber's salt:--

5 x 15
-------- = 0.75 gram Glauber's salt.
100

These quantities may be weighed out and added to the dye-bath, or if
solutions are kept, a calculation can be made as to the number of cubic
centimetres which contain the above quantities, and these measured out
and added to the dye-bath.

When all is ready, the bath is heated up, the swatch entered, and the
work of the test entered upon.

Students are recommended to make experiments on such points as:--

The shades obtained by using various proportions of dye-stuffs.

The influence of various assistants--common salt, soda, Glauber's salt,
borax, phosphate of soda--in the bath.

The influence of varying proportions of mordants on the shade of dyeing.

The value of various assistants, tartar, oxalic acid, lactic acid,
sulphuric acid, on the fixation of mordants.

The relative value of different ta