328 Practical Paper Making. 
the public, and every manufacturer is free to use it without 
any compensation whatever. 
DUSTERS.—The most simple apparatus consists of a _ 
truncated cone revolving upon the axis of the great circle 
and upon two rollers running in a groove round the crown 
of the small circle. This is covered with a-network of iron. 
The inner sides are armed with iron teeth arranged in a 
spiral, which force the rags out by the end opposite that of 
entrance. This kind of duster will only answer for fine 
clean and half clean rags. 
To render the action of this instrument more energetic, 
a tree is placed within, bearing iron spokes arranged in a 
spiral. These spokes force the rags against the wire-netting, 
which revolve in an opposite direction from that of the rota- 
tion of the tree. This contrivance for dusting, of a conical 
or cylindrical form, is preferable for foul and soiled rags, 
hems, seams, &c. It naturally requires more power than 
the first mentioned machine. When the duster is cylin- 
drical, it is given an inclination of from 25° to 40°; anda 
diameter of 0790 to 1:40 metres (2°95 to 3'60 ft.) by 4°50 to 
5.0 metres (14°76 to 16°50 ft.) in length. 
The wolf (loup briseur) serves to divide and clean the 
wastings of flax, hemp, oakum, coarse rags containing straw, 
or hemp and ropes. It is constructed upon the same prin- 
ciple as the preceding apparatus, and offers a resistance 
proportioned to the work it has to do. The iron axis 
armed with spokes is alone movable, and the impurities fall 
through an iron grating. 
The loss of material caused by this engine is at times so 
considerable that it has been discontinued in some paper 
mills. It nevertheless facilitates the operation of boiling, 
and various other manipulations by disintegrating the rag 
filaments, and rendering them more susceptible to the ac- 
tion of the lyes. These rags are softer and more easily re- 
duced to pulp. The machine requires great power, which 
many mills are not able to bestow. 
Whatever may be the style of duster employed, it is in- 
dispensible that it should be covered over with a close 
wooden cage in order to retain the dust and other impuri- 
ties which, mixed with the rag fibres, are called wastings of 
the duster. It should be understood that as the quality of 
these wastings varies with the nature of the rags, it is im- 
portant not to dust on the same day rags that differ much 
in quality, so that the refuse may be collected only once a 
day. 
