Researches on Cellulose | Page 3

find also that many workers whose publications we notice in this
present volume quite ignore the plan of the work, though they make
use of its matter. We think it necessary to restate this plan, which, we
are satisfied, is systematic, and, in fact, inevitable. Cellulose is in the
first instance a structure, and the anatomical relationships supply a
certain basis of classification. Next, it is known to us and is defined by
the negative characteristics of resistance to hydrolytic actions and
oxidations. These are dealt with in the order of their intensity. Next we
have the more positive definition by ultimate products of hydrolysis, so
far as they are known, which discloses more particularly the presence
of a greater or less proportion of furfural-yielding groups. Putting all
these together as criteria of function and composition we find they
supply common or general dividing lines, within which groups of these
products are contained. The classification is natural, and in that sense
inevitable; and it not only groups the physiological and chemical facts,
but the industrial also. We do not propose to argue the question
whether the latter adds any cogency to a scientific scheme. We are
satisfied that it does, and we do not find any necessity to exclude a
particular set of phenomena from consideration, because they involve
'commercial' factors. We have dealt with this classification in the
original work (p. 78), and we discuss its essential basis in the present
volume (p. 28) in connection with the definition of a 'normal' cellulose.
But the 'normal' cellulose is not the only cellulose, any more than a
primary alcohol or an aliphatic alcohol are the only alcohols. This point

is confused or ignored in several of the recent contributions of
investigators. It will suffice to cite one of these in illustration. On p. 16
we give an account of an investigation of the several methods of
estimating cellulose, which is full of valuable and interesting matter.
The purpose of the author's elaborate comparative study is to decide
which has the strongest claims to be regarded as the 'standard' method.
They appear to have a preference for the method of Lange--viz. that of
heating at high temperatures (180°) with alkaline hydrates, but the
investigation shows that (as we had definitely stated in our original
work, p. 214) this is subject to large and variable errors. The adverse
judgment of the authors, we may point out, is entirely determined on
the question of aggregate weight or yield, and without reference to the
ultimate composition or constitution of the final product. None of the
available criteria are applied to the product to determine whether it is a
cellulose (anhydride) or a hydrate or a hydrolysed product. After these
alkali-fusion processes the method of chlorination is experimentally
reviewed and dismissed for the reason that the product retains
furfural-yielding groups, which is, from our point of view, a particular
recommendation, i.e. is evidence of the selective action of the chlorine
and subsequent hydrolysis upon the lignone group. As a matter of fact
it is the only method yet available for isolating the cellulose from a
lignocellulose by a treatment which is quantitatively to be accounted
for in every detail of the reactions. It does not yield a 'normal' cellulose,
and this is the expression which, in our opinion, the authors should
have used. It should have been pointed out, moreover, that, as the
cellulose is separated from actual condensed combination with the
lignone groups, it may be expected to be obtained in a hydrated form,
and also not as a homogeneous substance like the normal cotton
cellulose. The product is a cellulose of the second group of the
classification. Another point in this investigation which we must
criticise is the ultimate selection of the Schulze method of prolonged
maceration with nitric acid and a chlorate, followed by suitable
hydrolysis of the non-cellulose derivatives to soluble products. Apart
from its exceptional inconvenience, rendering it quite impracticable in
laboratories which are concerned with the valuation of cellulosic raw
materials for industrial purposes, the attack of the reagent is complex
and ill-defined. This criticism we would make general by pointing out

that such processes quite ignore the specific characteristics of the
non-cellulose components of the compound celluloses. The second
division of the plan of our work was to define these constituents by
bringing together all that had been established concerning them. These
groups are widely divergent in chemical character, as are the compound
celluloses in function in the plant. Consequently there is for each a
special method of attack, and it is a reversion to pure empiricism to
expect any one treatment to act equally on the pectocelluloses,
lignocelluloses, and cutocelluloses. Processes of isolating cellulose are
really more strictly defined as methods of selective and regulated attack
of the groups