ES. The course of
industrial development in the 19th century has been one of enormous
expansion in use and considerable refinement in methods of preparation
and manufacture. Efforts to introduce new forms of cellulose have had
little result. Rhea or ramie has been a favourite subject of
investigation; the industry has been introduced into England, and
doubtless its development is only a question of time, as on the
continent of Europe the production of rhea yarns is well established,
though it is still only a relatively small trade--probably two or three
tons a day total production. The paper trade has required to seek new
sources of cellulose, in consequence of the enormous expansion of the
uses of paper. Important phases of development were: (1) in the period
of 1860 to 1870, the introduction of esparto, which has risen to a
consumption of 250,000 tons a year in the United Kingdom, at which
figure it remains fairly steady; (2) the decade 1870 to 1880, which saw
the development of the manufacture of cellulose from coniferous woods,
and this industry now furnishes a staple of world-wide consumption,
though the industry is necessarily localized in countries where the
coniferous woods are available in large quantities. As a development of
the paper industry we must mention the manufacture of paper textiles,
based upon the production of pulp yarns. Paper pulps are worked into
flat strips, which are then rolled into cylindrical form, and by a final
twisting process a yarn is produced sufficiently strong to be employed
in weaving.

What we may call the special cellulose industries depend upon specific
chemical properties of cellulose, partly intrinsic, partly belonging to
the derivatives such as the esters. Thus the cellulose nitrates are the
bases of our modern high explosives, as well as those now used for
military purposes. Their use has been steadily developed and perfected
since the middle of the 19th century. The industries in celluloid,
xylonite, &c., also depend upon the nitric esters of cellulose, and the
plastic state which they assume when treated with solvent liquids, such
as alcohol, amyl acetate, camphor and other auxiliaries, in which state
they can be readily moulded and fashioned at will. They have taken an
important place as structural materials both in useful and artistic
applications. The acetates of cellulose have recently been perfected,
and are used in coating fine wires for electrical purposes, especia