Part III.] Raitt : Bamboo as Material for Paper-pulp. 
29 
The quantity of combined chemicals required is 1 per cent, more than 
with straight soda liquor in order to maintain the minimum amount of 
NaOH necessary for digestion, but the extra cost of this is more than 
counterbalanced by the lesser cost of sulphate liquor, amounting to about 
Rs. 67 per ton of dry contents against Rs. 75 for soda liquor, its unit cost 
being 4*5 (bamboo—1). The superiority of sulphate treatment is shown 
very markedly in the above table in the great reduction effected in bleach¬ 
ing cost, as also in a small gain in yield. The unbleached pulp is a light 
brown in colour, whereas that from the straight soda treatment is dark 
brown, and there is also an improvement in softness and in strength. 
For comparison of these results with those obtainable with chipped 
material not starch extracted, and with straight soda treatment the 
following may be quoted in the case of B. polymorpha :— 
Chipped with nodes :—digestion quite impossible within an economic cost. 
Chipped, nodes excluded :—NaOH 25 per cent., unbleached yield 42, B. P. 36 
per cent. (=15*12 on raw material), bleached yield 39 per cent., unit 
cost 8*99. 
As with the results in Table VII, the same remarks regarding bleaching 
(paragraph 31) apply to Table VIII, i.e., the standard of colour is a brilli¬ 
ant white and the highest possible without serious loss of fibre by 
oxidation. A fair white suitable for many, and a good white suitable for 
most, of the uses to which it will be put can be obtained with 10 and 13 
per cent. B. P. respectively. There can be no hesitation in declaring 
the sulphate method of treatment to be the best for bamboo both in cost 
and in quality of product. The high degree of purity of the product is 
attested by the following analysis in the unbleached condition :— 
Mineral matter (ash) . . . . . . 1*68 
Hydrocellulose (soluble in alkali). . . . 4*37 
Cellulose . . . . . • • . 91*64 
Lignin (by difference) . . . . . 2*31 
100-00 
In unbleached sulphite wood pulp cellulose rarely reaches 89 per cent, 
and is frequently as low as 80 per cent. 
SECTION D. 
Microscopical. 
34. The capillary tubes or pores alluded to in paragraph 5 (see also 
Plate II, g) which we have found to be so important a feature in 
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