e, the cellulose when
regenerated re-aggregates a large proportion of these lower grade
celluloses, and the final loss is as stated above, from 5 to 7 p.ct.
only.

Secondly, it is found that all the conditions obtaining in the
alkali-cellulose stage affect the subsequent viscose reaction and the
properties of the final solution. The most important are obviously the
proportion of alkali to cellulose and the length of time they are in
contact before being treated with carbon disulphide. An excess of
alkali beyond the 'normal' proportion--viz. 2NaOH per 1 mol.
C_{6}H_{10}O_{5}--has little influence upon the viscose reaction, but
lowers the viscosity of the solution of the sulphocarbonate prepared
from it. But this effect equally follows from addition of alkali to the
viscose itself. The alkali-cellulose changes with age; there is a
gradual alteration of the molecular structure of the cellulose, of which
the properties of the viscose when prepared are the best indication.
There is a progressive loss of viscosity of the solution, and a
corresponding deterioration in the structural properties of the
cellulose when regenerated from it--especially marked in the film form.
In regard to viscosity the following observations are typical:--

(a) A viscose of 1.8 p.ct. cellulose prepared from an
alkali-cellulose (cotton) fourteen days old.

(b) Viscose of 1.8 p.ct. cellulose from an alkali-cellulose
(cotton) three days old.

(c) Glycerin diluted with 1/3 vol. water.

a b b c
Diluted with
equal vol.
water
Times of flow of equal volumes from 112 321 103 170
narrow orifice in seconds

Similarly the cellulose in reverting to the solid form from these
'degraded' solutions presents a proportionate loss of cohesion and
aggregating power expressed by the inferior strength and elasticity of
the products. Hence, in the practical applications of the product where
the latter properties are of first importance, it is necessary to adopt
normal standards, such as above indicated, and to carefully regulate all
the conditions of treatment in each of the two main stages of reaction,
so that a product of any desired character may be invariably obtained.

Incidentally to these investig