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PAPER TESTING
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characteristics can be easily observed. The fibres are reduced in diameter as well as in length by prolonged beating for strong papers, the ends are frayed, and it is not easy to identify the cotton in a finely-beaten rag mixture (Figs. 17 and 18).

Linen.—Fibre 30 to 40 mm. x .025 mm. Stained violet-red to brown. Linen is the fibre from the stem of the flax. The fibres have thicker walls than cotton, from which it is easily distinguished in its unbeaten state, being a smoother, rounder fibre, with marks like joints at intervals, small cross markings, and pointed ends. When beaten finely it is not possible to distinguish linen from cotton (Figs. 17 and 18).

Hemp.—Fibre 20 mm. x .02 mm. Stained, unbleached fibre, yellow to brown; bleached, brown-red to wine-red. In general appearance the fibre is similar to linen, with slightly thinner walls, more markings, and at the places where joint markings occur are also little hairs. The ends of the fibres are rounded or flattened. The fibre in paper is usually beaten so finely as not to be recognised (Fig. 19).

Manilla Hemp.—Fibre 7 mm. x .02 mm. Stained yellow to blue, according to amount of bleaching and cleaning of the raw material. The fibres are like hemp fibres, but the canal is much larger, and accompanying the fibres are many oblong transparent cells, sometimes occurring like blocks of bricks (Fig. 20).

Jute.—Fibre 2.5 mm. x .022 mm. Stained, unbleached, yellow; bleached, brown. Jute fibres resemble linen and hemp, but the central canal is irregular in width, widening in places and narrowing again. The ends of the fibres are pointed and somewhat flattened (Fig. 21).

Straw.—Fibre 1.5 mm. x .015 mm. Stained greyish to blue. Similar to esparto, but the fibres are more flexible, and become kinked when made into