nt, oxalic acid only rarely.

The dyeing with mordant dyes must be done in a special way and with
great care, if uniform, level shades and fast colours are to be
obtained.

The dye-bath must be started cold, and the wool be entered and worked
for twenty to thirty minutes, the object being to cause the dye-stuffs
to penetrate well into the substance of the fibre, then the
temperature is slowly raised to the boil, not less than three-quarters
of an hour being taken in doing so; the temperature is maintained at
the boil for fully one and a half hours longer. During the boiling
operation the mordant and dye-stuff combine together, and form the
characteristic colour lake, and the boiling fixes this firmly on to
the wool.

The water used plays a very important part. If too hard in character,
the lime it contains shows a tendency to combine with the (p. 118)
dye-stuff and form a colour lake, which is deposited in a loose form
on the wool or in the bath, tending to make the shades dull and loose
to rubbing. This defect can be remedied by adding a little acetic acid
to the dye-bath, say about 3 lb. to 100 gallons of the water. It
combines with and neutralises the influence of the lime, in so far as
the formation of a loose colour lake is concerned; still the lime does
unite with the dye-stuff, but the combination is formed more slowly,
and in or on the wool fibre so that it is fast.

By working in the manner laid down above very fast shades can be dyed
on wool with mordant dyes, and the following recipes will give the
other details as to tints, shades, quantities, etc., not noted above.

_Claret_.--Mordant, 2 lb. bichromate of potash and 2 lb. tartar; dye,
8 lb. Alizarine Claret R.

_Fawn_.--Mordant, 3 lb. bichromate of potash and 1-1/2 lb. tartar;
dye, 3 lb. Alizarine Orange N.

_Maroon_.--Mordant, 3 lb. bichromate of potash and 2-1/2 lb. tartar;
dye, 15 lb. Alizarine Orange N.

_Deep Crimson_.--Mordant, 3 lb. bichromate of potash and 2-1/2 lb.
tartar; dye, 8 lb. Alizarine Red 1 W S.

_Lilac Rose_.--Mordant, 1-1/2 lb. bichromate of potash and 1-1/2 lb.
tartar; dye, 1 lb. Alizarine Red 1 W S.

_Crushed Strawberry Tint_.--Mordant, 2 lb. bichromate of potash and
1-1/2 lb. tartar; dye, 3 lb. Alizarine Red 2 W S.

_Deep Claret_.--Mordant, 3 lb. bichromate of potash and 2-1/2 lb.
tartar; dye, 5 lb. Alizarine Red 1 W S.

_Bright Fawn Red_.--Mordant, 2 lb. bichromate of potash and 1-1/2 lb.
tartar; dye, 1 lb. A