every portion of them brought into intimate contact with the
dye-liquor. The continuance of the dyeing operations for one and a
half to two hours after the vat has reached the boil is necessary to
properly develop and fix the colour on the fibre; a short boil leaves
the goods of a poor shade, without any solidity about it, and the
colour is loose, while a longer boil brings up a solid shade and a
fast colour.

Although it is not absolutely necessary to add any acid to the
dye-bath during the dyeing operations, yet as the Alizarines and most
of this class of dye-stuffs dye better in a slightly acid bath it is
advisable to add a small quantity of acetic acid, say about one pint
to every 100 lb. of goods; this serves to correct any alkalinity of
the water, which may be due to its containing any lime. Dye-stuffs of
the acid class, such as indigo extract, Cloth red, Acid magenta, etc.,
may be used along with the Alizarine dye-stuffs, in which case the
addition of acid to the dye-bath becomes necessary, but too great an
excess of acid should be avoided, as it interferes somewhat with the
dyeing of the mordant dyes.

This is by far the best and most generally used method of applying
these mordant dyes. It is not a costly process, being indeed economical,
as it only requires just the right amounts of drugs and dye-stuffs,
and there is the minimum loss of material in the mordanting and
dye-baths. Shades can be brought up with the greatest ease, although
it is well in the dyeing to add rather less dye-stuff than is (p. 074)
actually required, and to add more when it is seen how the shade is
coming up. The labour is the most important item in the mordanting and
dyeing method.

The proportions of material used to the weight of the wool are: Of
bichromate of potash, 3 per cent. for full shades, and 1 per cent. for
pale shades; of fluoride of chrome, the same quantities; of acetate of
chrome, according to the strength of the solution used; of alum, 10 to
20 per cent.; of sulphate of alumina, 5 to 10 per cent.; of copperas,
5 to 10 per cent.; of tartar, 1-1/2 to 2-1/2 per cent.; of oxalic
acid, 1 to 1-1/2 per cent.; of sulphuric acid, 1 per cent.; of argol,
2-1/2 to 5 per cent.; of tartaric acid, 1 to 1-1/2 per cent.; but of
course in an article like this it is impossible to give definite
quantities.

_Second Method_. #Stuffing and Saddening.#--This method consists in
first treating the wool with a solution of the dye-stuff