e resolution. Chromic acid in dilute
solutions combines with the lignone complex, but in presence of
hydrolysing acids total oxidation of the lignone is determined. The
principal products are oxalic, carbonic, formic and acetic acids. This
reaction is an index of constitution. Generally, the lignone is attacked
under many conditions and by many reagents which are without action upon
cellulose, by virtue of its unsaturated constitution, and its acid and
aldehydic residues.

_Cuto-cellulose._--A typical cuto-cellulose is the cuticle (peel) of the
apple which, when purified by repeated hydrolytic treatment and finally
by alcohol and ether, gives a product of the composition C = 75.66%, H =
11.37%, O = 14.97%. Hydrolysis by strong alkalis gives stearo-cutic
acid, C28H48O4, and oleo-cutic acid, C14H20O4 (Fremy). Cork is a complex
mixture containing various compound celluloses: extraction with alcohol
removes certain fatty alcohols and acids, and aromatic derivatives
related to tannic acid; the residue is probably a mixture of cellulose,
ligno-cellulose, cerin, C20H32O and suberin; the latter yields stearic
acid, C18H36O2 and the acid C22H42O3. The cuto-celluloses have been only
superficially investigated, and, with the exception of cork, are of but
little direct industrial importance.

_Industrial Uses of Cellulose_.--The applications of cellulose to the
necessities of human life, infinitely varied in kind as they are
colossal in magnitude, depend upon two groups of qualities or
properties, (1) structural, (2) chemical. The manufactures of vegetable
textiles and of paper are based upon the fibrous forms of the naturally
occurring celluloses, together with such structural qualities as are
expressed in the terms strength, elasticity, specific gravity. As
regards chemical properties, those which come into play are chiefly the
negative quality of resistance to chemical change; this is obviously a
primary factor of value in enabling fabrics to withstand wear and tear,
contact with atmospheric oxygen and water, and such chemical treatments
as laundrying; positive chemical properties are brought into play in the
auxiliary processes of dyeing, printing, and the treatment and
preparation in connexion with these. Staple textiles of this group are
cotton, flax, hemp and jute; other fibres are used in rope-making and
brush-making industries. These subjects are treated in special articles
under their own headings and in the article FIBR