26 
Indian Forest Records. 
[Vol. Ill 
The 16 per cent, of NaOH used for No. I represents the minimum 
necessary to secure digestion. The addition of 2 per cent, excess in 
No. II is fully justified, the yield being nearly the same and the unit cost 
reduced by the lesser consumption of B. P. So also with 4 per cent, 
excess in No. Ill where the unit cost is still further reduced in spite of 
substantial fibre loss beginning to appear. With 6 per cent, excess in 
No. IV the economic limit has been passed, the fibre loss being more 
than the saving in B. P. is worth. It would therefore appear that a 
4 per cent, excess added for bleaching effect is as much as economy will 
permit, and this conclusion is fully borne out by the whole series of 
digester tests which followed, the final average results being asunder :— 
TABLE VII. 
Digestion results with NaOH in excess of amount required for resolution 
of non-cellulose : Crushed, starch-free bamboo. 
Temperature, pressure and time as per Table VI. 
— 
NaOH. 
Un¬ 
bleached 
yield. 
j B. 
P. 
Unit 
cost. 
Per 
cent. 
Tw. 
1 (a) 
Per 
cent. 
(6) 
Per 
cent. 
Bleached 
yield. 
B. Tulda 
m 
14 
44-0 
23 
10-1 
42-0 
6-94 
B. arundinacea ] 
21 
12i 
43-0 
25 
10-8 
40-8 
7 23 
B. polymorpha 
19| 
14 
45-5 
25 
11-4 
43-0 
6-82 
C . pergracile . 
20 
12 j 
44-5 
23 
10-2 
42-3 
6-73 
Melocanna b. . 
24 
13 1 
43-0 
27 
11-6 
41-0 
7-42 
(а) Per cent, on unbleached pulp. 
(б) Per cent, on raw material. 
The unit cost in each case is less than in Table VI and it is noticeable 
that the yields of the species are in closer agreement than the analytical 
results would lead us to expect, lending support to the supposition that if 
it were possible to accurately estimate the resistant a-cellulose, its quan¬ 
tity would be found to be practically the same for all species, the analy¬ 
tical variations being due to variable amounts of /3-cellulose. 
[ 206 ] 
