Researches on Cellulose | Page 8

employed, though the composition of the product is more or less
divergent from a 'pure cellulose.'
Dilute nitric acid at 60-80° (Cross and Bevan) and a dilute mixture of
nitric and sulphuric acids (Lifschutz) have been employed for isolating
cellulose from the lignocelluloses. Hoffmeister modifies the method of
Schulze by substituting hydrochloric acid for the nitric acid. Treatment
with the halogens associated with alkaline processes of hydrolysis is
the basis of the methods of Hugo Muller (bromine water) and Cross
and Bevan (chlorine gas). Lastly, the authors notice the methods based
upon the action of the alkaline hydrates at high temperatures (180°) in
presence of water (Lange), or of glycerin (Gabriel). The process of
heating to 210° with glycerin only (Hönig) yields a very impure and
ill-defined product.
For comparative investigation of these processes certain celluloses and
cellulosic materials were prepared as follows:
(a) 'Rag' cellulose.--A chemical filter paper, containing only cotton and
linen celluloses, was further purified by boiling with dilute acid and
dilute alkali. After thorough washing it was air-dried.
(b) Wood cellulose.--Pine wood sawdust was treated by digestion for

fourteen days with dilute nitric acid with addition of chlorate (Schulze).
The mass was washed and digested with alkaline lye (1.25 p.ct. KOH),
and exhaustively washed, treated with dilute acetic acid; again washed,
and finally air-dried.
This product was found to yield 2.3 p.ct. furfural on distillation with
HCl (1.06 sp.gr.).
(c) Purified wood.--Pine wood sawdust was treated in succession with
dilute alkalis and acids, in the cold, and with alcohol and ether until
exhausted of products soluble in these liquids and reagents.
In addition to the above the authors have also employed jute fibre and
raw cotton wool in their investigations.
They note that the yield of cellulose is in many cases sensibly lowered
by treating the material after drying at the temperature of 100°. The
material for treatment is therefore weighed in the air-dry condition,
and a similar sample weighed off for drying at 100° for determination
of moisture.
The main results of the experimental investigation are as follows:--
Weende process further attacks the purified celluloses as follows:
Wood cellulose losing in weight 8-9 p.ct.; filter paper, 6-7.5 p.ct., and
the latter treated a second time loses a further 4-5 p.ct. It is clear,
therefore, that the process is of purely empirical value.
Schulze.--This process gave a yield of 47.6 p.ct. cellulose from pine
wood. The celluloses themselves, treated by the process, showed losses
of 1-3 p.ct. in weight, much less therefore than in the preceding case.
Hönig's method of heating with glycerin to 210° was found to yield
products very far removed from 'cellulose.' The process may have a
certain value in estimations of 'crude fibre,' but is dismissed from
further consideration in relation to cellulose.
Lange.--The purpose of the investigation was to test the validity of the

statement that the celluloses are not attacked by alkaline hydrates at
180°. Experiments with pine wood yielded a series of percentages for
cellulose varying from 36 to 41; the 'purified wood' gave also variable
numbers, 44 to 49 per cent. It was found possible to limit these
variations by altering the conditions in the later stages of isolating the
product; but further experiments on the celluloses themselves
previously isolated by other processes showed that they were
profoundly and variably attacked by the 'Lange' treatment, wood
cellulose losing 50 per cent. of its weight, and filter paper (cellulose)
losing 15 per cent. Further, a specimen of jute yielded 58 per cent. of
cellulose by this method instead of the normal 78 per cent. It was also
found that the celluloses isolated by the process, when subjected to a
second treatment, underwent a further large conversion into soluble
derivatives, and in a third treatment further losses of 5-10 per cent
were obtained. The authors attach value, notwithstanding, to the
process which they state to yield an 'approximately pure cellulose,' and
they describe a modified method embodying the improvements in detail
resulting from their investigation.
Gabriel's method of heating with a glycerin solution of alkaline hydrate
is a combination of 'Hönig' and 'Lange.' An extended investigation
showed as in the case of the latter that the celluloses themselves are
more or less profoundly attacked by the treatment--further that the
celluloses isolated from lignocelluloses and other complex raw
materials are much 'less pure' than those obtained by the Lange
process. Thus, notably in regard to furfural yielding constituents, the
latter yield 1-2 p.ct. furfural, whereas specimens of 'jute cellulose'
obtained by the Gabriel process were found to yield 9 to 13 p.ct.
furfural.
Cross and Bevan.--Chlorination process yielded in the hands of the
authors results confirming the figures given in 'Cellulose' for yield of
cellulose. Investigation of the products for yield of furfural, gave 9 p.ct.
of this aldehyde showing the presence of