ttons (see p. 23). It is quite probable that chemical as well
as structural factors co-operate in further differentiating the cottons.

Further investigation of the influence upon the benzoate reaction, of
increase of concentration of the soda lye, used in the preliminary
alkali cellulose reaction, from 20 to 33 p.ct. NaOH, established (1)
that there is no corresponding increase in the benzoylation, and (2)
that this ester reaction and the sulphocarbonate reaction are closely
parallel, in that the degree and limit of reaction are predetermined by
the conditions of formation of the alkali cellulose.

_Monobenzoate_ prepared as above described is resistant to all solvents
of cellulose and of the cellulose esters, and is therefore freed from
cellulose by treatment with the former, and from the higher benzoate by
treatment with the latter. Several of these, notably pyridine, phenol
and nitrobenzene, cause considerable swelling and gelatinisation of the
fibres, but without solution.

_Structureless celluloses_ of the 'normal' type, and insoluble therefore
in alkaline lye, treated under similar conditions to those described
above for the fibrous celluloses, yield a higher proportion of
dibenzoate. The following determinations were made with the cellulose
(hydrate) regenerated from the sulphocarbonate:--

Mol. proportions of reagents Yield Dibenzoate p.ct.
C_{6}H_{10}O_{5} : 2NaOH : 2BzCl 145 34.7
[Caustic soda at 10 per cent. NaOH]

C_{6}H_{10}O_{5} : 4NaOH : 2BzCl 162 62.7
[Caustic soda at 20 per cent. NaOH]

_Limit of reaction._--The cellulose in this form having shown itself
more reactive, it was taken as the basis for determining the maximum
proportion of OH groups yielding to this later reaction. The systematic
investigations of Skraup [Monatsh. 10, 389] have determined that as
regards the interacting groups the molecular proportions 1 OH : 7 NaOH :
5 BzCl, ensure complete or maximum esterification. The maximum of OH
groups in cellulose being 4, the reagents were taken in the proportion
C_{6}H_{10}O_{5} : 4 [7 NaOH : 5 BzCl]. The yield of crude product, after
purifying as far as possible from the excess of benzoic acid, was 240
p.ct. [calculated for dibenzoate 227 p.ct.]. On further investigating
the crude product by treatment with solvents, it was found to have still
retained benzoic acid. There was also present a proportion of only
partially attacked cellul