7).

(p. 273) A series of three lectures, in which the more important
industries in cellulose and its derivatives are dealt with on their
scientific foundations, and by means of a selection of typical problems.
In reference to textiles, the small number of vegetable fibres actually
available, out of the endless variety afforded by the plant world, is
referred to the number of conditions required to be fulfilled by the
individual fibre, thus: yield per cent. of harvested weight or per unit
of field area, ease of extraction, the absolute dimensions of the
spinning unit, and the proportion of variation from the mean dimensions;
the relative facility with which the unit fibre can be isolated
preparatory to the final twisting operation; the chemical constants of
the fibre substance, especially the percentage of cellulose and degree
of resistance to hydrolysis. It is suggested that any important addition
to the very limited number fulfilling the conditions, or any great
improvement in these, can only result from very elaborate artificial
selection and cultural developments on this basis.

The paper making fibres are shown to fall into a scheme of
classification based on chemical constitution, and consisting of the
four groups: (a) Cotton [flax, hemp, rhea], (b) wood celluloses,
(c) esparto, straw, and (d) lignocelluloses. Papers being exposed to
the natural disintegrating agencies, more especially oxygen, water (and
hydrolysing agents generally), and micro-organisms, the relative
resistance of the above groups of raw materials is discussed as an
important condition of value. The indirect influence of the ordinary
sizing and 'filling' materials is discussed. The paper-making quality of
the fibrous raw materials is also discussed, not merely from the point
of view of the form and dimensions of the ultimate fibres, but their
capacity for 'colloidal hydration.' This is complementary to the action
of rosin, i.e. resin acids, in the engine-sizing of papers; and the
proof of the potency of this factor is seen in the superior effects
obtained in sizing jointly with solutions of cellulose and, more
particularly, viscose and rosin. Wurster's much-cited monograph of the
subject of rosin-sizing ['Le Collage des Papiers,' Bull. Mulhouse, 1878]
neglects to take into consideration the contribution of the cellulose
hydrates to the total and complex sizing effect, and hence gives a
partial view only of the function of the resin acids.

In