e dye vessel. The great
attraction of silk for these colors simplifies silk dyeing
exceedingly. The sad colors, on the other hand, and especially black,
are in many cases exceedingly complex, the main object of the dyer
being not so much to color the silk as to increase its weight.

Dyeing black on silk is unquestionably the most important branch of
silk dyeing, and it has probably received more attention than any
other branch, in consequence of which it has been brought to a high
degree of perfection. Blacks on silks are produced both from natural
and artificial coloring matters, the former having, so far, retained
their pre-eminence despite the recent discoveries of chemists. For
various reasons coal-tar colors have never proved successful in dyeing
black on silk. Since the discovery of America, logwood blacks have
formed the staple of the black-silk dyer, who has carried their
production to a high degree of excellence. But unfortunately, besides
aiming at a high state of perfection in the actual dyeing operation,
the black-silk dyer has also aimed at increasing the weight of the
dyed silk, so that nowadays it is possible for him to receive ten
pounds of raw silk and to send out fifty pounds of black silk, the
extra forty pounds being additions made in the process of dyeing.

[Illustration: WINDING SILK ON SWIFTS]

Logwood black-silk dyeing consists essentially of alternate dippings
in separate baths with the mordant and dyestuffs suitable for
producing the required color and weight. The number of dippings and
the length of time taken in each operation depend on the intensity of
the black wanted and the amount of weighting which is desired. The
chief substances used for weighting are lead salts, catechu, iron, and
nut-galls, with soap and oil to soften in some degree the harshness of
the fabric which these minerals cause. As the details of the
operations are practically the same for all kinds of logwood blacks
(raven, jet, crape, dead black, etc.), the method for producing one
will suffice for all. The process involves several distinct
operations, as follows:

1. =The Boiling Off.= This is the removal of the gum and natural
coloring matter in the silk. It is accomplished by boiling the skeins
of silk in water and good olive oil soap for about one hour. This
dissolves the gum and leaves the fiber clean and glossy.

2. =Mordanting.= This is done in a bath of nitrate of iron, in which
the skeins of silk are allowed