APPENDIX
MOISTURE REMOVED BY THE COUCH ROLLS

363

It is sometimes asserted that the couch rolls do not remove any appreciable
amount of water from the web. This is not so. The result of several tests
showed that about 10 per cent of water is removed, or the proportion of water
to fibre is almost halved.

Moisture in web before couch roll 86.85 per cent, or 6.60 parts water per
part fibre.

Moisture in web after couch roll 78.64 per cent, or 3.68 parts water per
part fibre.

The moisture content is estimated on the wet pulp weight.

The paper was pure sulphite and the substance 24^ Ib. demy.

COLOUR REACTIONS OF FIBRES BY COMMON STAINS

Fibre
Iodine and Zinc Chloride
Iodine and Sulphuric Acid
Aniline Sulphate
Phloro-gludnol

Cotton .......... Flax .......... Hemp ' .......... Jute ............
Violet Violet Violet Brown yellow
Blue Blue Blue Green blue
Pale yellow Golden yellow
Violet red Deep red

Ramie .......... Manilla hemp ........ New Zealand flax ...... Chemical wood ........ Mechanical wood ........ ,
Dull violet Yellow to violet Golden yellow Blue violet Yellow
Dull blue
Green blue Blue to grey Dark yellow
YeUow •Yellowish Pale yellow Dark yellow
Red Pale red Pale red Deep red

Iodine and Zinc Chloride (Herzberg Stain). Dissolve 20 grins, zinc chloride in
10 ml. water and add to a solution of 2.1 grms. potassium iodide and o.i grm.
iodine in 5 ml. water. Allow to stand for 24 hours and decant the clear
solution, and finally add a crystal of iodine to the clear solution. Place a drop
of the solution on the disintegrated and teased fibres and mop up the excess
stain to avoid too deep a colouration.
Iodine and Sulphuric Acid. Dissolve 2.85 grms, iodine and 5.0 grms. potassium
iodide in 100 ml. water. Add 5 ml. glycerine.
Spot the fibre mass with the iodine solution, mop up the excess stain after
standing two minutes, and add a spot of sulphuric acid solution (70 ml. con-
centrated sulphuric acid added to 30 ml. water).
Aniline Sulphate. Dissolve I grm. aniline sulphate in 50 ml. water and apply
solution as with iodine stains.
Phloroglucinol. Dissolve i grm. phloroglucinol hydrochloride in 50 ml.
ethyl alcohol and add 25 ml. concentrated hydrochloric acid. Apply the stain
as with iodine stains.