748 Journal of Agriculture, Victoria. [10 Dec, 1918. 



this type are, therefore, obtained from Dicotyledons (flax, hemp, jute), 

 for the most part. Monocotyledons yield coarser, weaker, darker, or 

 more irregular and rougher fibres of less commercial value (coir, raffia). 

 New Zealand flax (Phormium tenax) is one of the few exceptions, but 

 is at a disadvantage owing to its slow growth under cultivation. 



The third class of fibre is derived from the fibres of wood tissue, 

 and, as a general rule, is employed only for making paper pulp, but has 

 been used in various ways in Germany for weaving to make good the 

 deficiency of proper textile fibres. For wood pulp the fibres should be 

 at least 1 to 4 millimetres long, they must be easily separated by 

 mechanical or chemical treatment, and must, therefore, not be too 

 strongly cemented together, and the less lignified the fibres are, and the 

 more they consist of unaltered cellulose, the better. 



Bearing the above facts in mind, it may be worth while to consider 

 how far the native plants which have been put forward as fibre plants 

 comply with the above conditions and requirements as possible com- 

 mercial sources of fibre. 



Eucalyptus Barks as Fibre-yielding Barks for Paper Making. — The 

 first statements to this effect appear to have been made some 30 years 

 ago by Baron von Mueller, and apparently were intended as statements 

 of possibility rather than as statements of fact. Since then, owing to 

 the increased use of wood pulp for paper making, many once promising 

 materials have lost all value for this purpose. The original statements 

 have, however, been repeated again and again more and more dogmatic- 

 ally without further investigation of the actual economic value of such 

 materials. 



In some respects the barks of Eucalypts have precisely those qualities 

 which should not be present in good paper-pulp materials. Thus the 

 presence of insoluble gum, resin, or kino, or of a high percentage of 

 tannin or colouring materials is a serious disqualification for paper-pulp 

 purposes. The pulp must be capable of ready bleaching without treat- 

 ment so severe as to damage the fibres, lessen their strength, or cause 

 their walls to swell. Finally, the bark must not contain suberinized 

 tissue mixed up with the fibres, as is the case with the stringy barks. 

 The suberinized tissue is more resistant than the fibres to caustic soda 

 and retting, and can only be removed even partially by expensive me- 

 chanical methods. Until it is removed, a satisfactory pulp cannot be 

 obtained. 



Statements as to the value of the barks of Eucalypts for paper 

 making should, therefore, be received with great caution, unless definite 

 evidence is given of the actual manufacture, cost, and quality of the 

 paper supposed to be yielded by them. 



Eucalyptus ohliqua. — The bark is stated to be suitable for the manu- 

 facture of packing, printing, or even w^riting paper, as well as for mill 

 and paste boards, and the pulp is stated to bleach readily. As a matter 

 of fact, the fibres are red or brown in colour, are very weak, and cannot 

 be bleached readily by any cheap method without still further weaken- 

 ing them. As the bark contains large amounts of suberinized non- 

 fibrous tissue, it is unsuitable for paper making. The same applies to 

 Eucalyptus macrorrhyncha, the red stringy bark. 



