ose (monobenzoate). The soluble benzoate
amounted to 90 p.ct. of the product. It may be generally concluded that
the dibenzoate represents the normal maximum but that with the hydrated
and partly hydrolysed cellulose molecule, as obtained by regeneration
from the sulphocarbonate, other OH groups may react, but they are only a
fractional proportion in relation to the unit group C_{6}H_{10}O_{5}. In
this respect again there is a close parallelism between the
sulphocarbonate and benzoyl-ester reactions.

_The dibenzoate_, even when prepared from the fibrous celluloses, is
devoid of structure, and its presence in admixture with the fibrous
monobenzoate is at once recognised as it constitutes a structureless
incrustation. Under the microscope its presence in however minute
proportion is readily observed. As stated it is soluble in certain of
the ordinary solvents of the cellulose esters, e.g. chloroform, acetic
acid, nitrobenzene, pyridine, and phenol. It is not soluble in ether or
alcohol.

_Hygroscopic moisture of benzoates._--The crude monobenzoate retains
5.0-5.5 p.ct. moisture in the air-dry condition. After removal of the
residual cellulose this is reduced to 3.3 p.ct. under ordinary
atmospheric conditions. The purified dibenzoates retain 1.6 p.ct. under
similar conditions.

_Analysis of benzoates._--On saponification of these esters with
alcoholic sodium hydrate, anomalous results are obtained. The acid
numbers, determined by titration in the usual way, are 10-20 p.ct. in
excess of the theoretical, the difference increasing with the time of
boiling. Similarly the residual cellulose shows a deficiency of 5-9
p.ct.

It is by no means improbable that in the original ester reaction there
is a constitutional change in the cellulose molecule causing it to break
down in part under the hydrolysing treatment with formation of acid
products. This point is under investigation. Normal results as regards
acid numbers, on the other hand, are obtained by saponification with
sodium ethylate in the cold, the product being digested with the
half-saturated solution for 12 hours in a closed flask.

The following results with specimens of mono- and dibenzoate, purified,
as far as possible, may be cited:

Combustion results Saponification results
Calc. C_{6}H_{5}.COOH Calc. Cellulose Calc.
Monobenzoate C 56.60 58.65}
H 5.06 5.26} 46.0 45.9 58.0