be desired than that described above.

Dyeing experiments can be made with either yarns or pieces of cloth,
swatches as they are commonly called; a very convenient size is a
small skein of yarn or a piece of cloth weighing 5 grammes. These test
skeins or pieces ought to be well washed in hot water before use, so
that they 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 is 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 grammes per litre,
and then by means of a pipette any required quantity can be
conveniently added. The same might be followed in the case of dyes
which are constantly in use, in this case 5 grammes per litre will be
found strong enough.

Supposing it is desired to make a test of a sample of Acid Red, using
the following proportions, 2 per cent. dye-stuff, 3 per cent.
sulphuric acid and 15 per cent. Glauber's salt, and the weight of the
swatch which is being used is 5 grammes, 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) / 100 = 0.1 gramme of dye.

For the acid we have similarly (5 x 3) / 100 = 0.15 gramme of (p. 215)
acid.

For the Glauber's salt (5 x 15) / 100 = 0.75 gramme of Glauber's salt.

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 put in 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