Part III.] Raitt : Bamboo as Material for Paper-pulp . 
17 
that it stands in a class by itself. It has a greater starch storage power 
than any of them, has considerably less pectose and considerably more 
lignin. 
19. In its starch contents, bamboo differs entirely from any of the 
other materials in common use. As has already been remarked, season¬ 
ing reduces this considerably, but in thoroughly seasoned culms of all ages 
the average water solubles will still be about 9 to 10 per cent, except 
with Melocanna which will show 2 or 3 per cent. more. The proportion 
of solid to secondary starch products will vary according to whether the 
plant is storing or using plant food, but usually it will be cut at a 
season when the latter process is in progress. A detailed analysis of 
one cut at this period, wdiich showed 13*57 per cent, of w r ater solubles, 
gave the following figures :— 
Per cent. 
Starch, solid . . . . . . . 2-70 
Starch in secondary forms ..... 8*33 
Colouring matter and soluble salts .... 2*54 
13-57 
It might be assumed that as the whole of this is soluble in w r ater, the 
soda contents of the digestion liquor are unaffected by it. This, however, 
is not the case. In strong solutions, not under 4 per cent, of NaOH, it 
does neutralise a considerable amount, and, further, in doing so it com¬ 
bines to form an insoluble dark brown precipitate with the secondary 
products, (the combination with solid starch giving no ppt. or colour 
reaction), which the pulp filters out and which is unbleachable and seriously 
affects the final bleaching process with B. P. The amount of NaOH 
which it abstracts from the liquor I have found to be equal on the 
average to 1 per cent, on the raw material for each 4’5 per cent, of 
water solubles shown in analysis. Therefore, in the digestion of material 
containing 9 per cent, of water extract and requiring 18 per cent, of 
NaOH to effect complete digestion, 2 per cent, is used up by the starchv 
matter, and in the subsequent treatment with B. P., from 6 to 8 per 
cent, more B. P. will be required to bleach up to standard w T hite than 
would be necessary if the starch was not there. Since the whole is 
soluble in hot wrater, obviously the right course is to make a preliminary 
boiling in w T ater the first step in digestion. After thus exhausting the 
water solubles, the ordinary digestion can then proceed with a smaller 
quantity of NaOH. The large and variable content of starch is one of 
the important features indicating the necessity of considering bamboo as 
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