4 
Indian Forest Records. 
[VOL. Ill 
Tw. = Twaddel’s hydrometer for measuring density of liquids. Each 
degree corresponds to 5 degs. of specific gravity above that of water taken 
as 1,000. Thus 7 degrees Tw. means 1,035 sp. gr. 
Temperatures are quoted in terms of the centigrade thermometer : 
pressures in pound per square inch above normal atmospheric pressure. 
Digester results are given in per cent, of N. A. D. pulp from N. A. D. 
raw material: B.P. consumed, in per cent, on N. A. D. unbleached pulp 
except when otherwise stated. Standard white means the highest degree 
of whiteness to which the pulp can be bleached without incurring the risk 
of serious oxidation and loss of fibre. It may be described as a brilliant 
white, or full bleach, and is good enough for the highest grades of 
printing and writing paper. Unbleachable is used throughout in the 
sense of unbleachable within economic limits of cost. 
SECTION A. 
Physical. 
5. In structure, bamboo presents several features which markedly 
differentiate it from any of the raw materials now 
Structural. j n use> it j s porous, thereby differing from con¬ 
iferous wood; its pores* run vertically in close, straight and regular 
series throughout the culm, (see paragraph 34). They form capillary 
tubes, open throughout their whole length, which in the green culm 
are filled with sap, and in the dry with air. Dry bamboo is therefore 
largely impregnated with air in a state of capillarity, a condition render¬ 
ing its expulsion difficult. Drying and seasoning does not cause a col¬ 
lapse or flattening of these pores by shrinkage as is the case to a consider¬ 
able extent in cereal straws and the smaller annual grasses. In bamboo 
they retain their shape and size, and therefore their air holding capacity, 
and no other material in common use carries so large a quantity of 
imprisoned air. When a mass of bamboo chips is boiled in an open vessel 
and prevented from floating by being held under the water surface, the 
expelled air forms a dense dome of froth over the water. Spruce-wood 
chips similarly dealt with throw up a few air bubbles only. When not 
*Pores is here used to denote sap canals or conduits of comparatively large size, 
Visible to the naked eye or with a low power lens. One of them is shown on Plate II, (7- 
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