r foreign substance becomes fastened in
the strand of yarn while it is being spun, it either causes the thread
to break or renders it bunchy and uneven. For removing burs, etc.,
from the wool two methods are pursued: the one purely mechanical, the
other chemical, and known respectively as burring and carbonizing.

=Bur Picker.= For the mechanical removing of burs a machine called the
bur picker is employed. In this machine the wool is first spread out
into a thin lap or sheet; then light wooden blades, rotating rapidly,
beat upon every part of the sheet and break the burs into pieces. The
pieces fall down into the dust box or upon a grating beneath the
machine, and are ejected together with a good deal of the wool
adhering to them. Often the machine fails to beat out fine pieces and
these are scattered through the stock.

=Process of Carbonizing.= For the complete removal of all foreign
vegetable substances from wool the most effective process is
carbonizing, in which the burs, etc., are burned out by means of acid
and a high degree of heat. The method of procedure is as follows: The
wool to be treated is immersed in a solution of sulphuric or
hydrochloric acid for about twelve hours, the acid bath being placed
in cement cisterns or in large lead-lined tubs and not made strong
enough to injure the fiber of the wool. During the immersion the stock
is frequently stirred. Next, the wool is dried and then placed in an
enclosed chamber and subjected to a high temperature (75 degrees C.).
The result of this process is that all the vegetable matter contained
in the wool is "carbonized" or burned to a crisp, and on being
slightly beaten or shaken readily turns to dust. This dust is removed
from the wool by various simple processes. The carbonizing process was
first introduced in 1875, though it made but slight headway against
the old burring method until after 1880.

=Blending.= Pure wool of but one quality is not often used in the
production of woven fabrics, so, before the raw material is ready for
spinning into yarn, or for other processes by which it is worked into
useful forms, it is blended. Wools are blended for many reasons (among
which cheapness figures prominently), the added materials consisting
usually of shoddy, mungo, or extract fibers. Ordinarily, however,
blending has for its object the securing of a desired quality or
weight of cloth. The question of color, as well as quality, also
determines blending operat