r has been
accumulated in view of the ultimate contribution of the results to the
general theory of colloidal solutions. But viscose is a complex product
and essentially variable, through its pronounced tendency to progressive
decomposition with reversion of the cellulose to its insoluble and
uncombined condition. The solution for this reason does not lend itself
to exact measurement of its physical constants such as might elucidate
in some measure the progressive molecular aggregation of the cellulose
in assuming spontaneously the solid (hydrate) form. Reserving the
discussion of these points, therefore, we confine ourselves to recording
results which further elucidate special points.

_Normal and other celluloses._--We may certainly use the sulphocarbonate
reaction as a means of defining a normal cellulose. As already pointed
out, cotton cellulose passes quantitatively through the cycle of
treatments involved in solution as sulphocarbonate and decomposition of
the solution with regeneration as structureless or amorphous cellulose
(hydrate).

Analysis of this cellulose shows a fall of carbon percentage from 44.4
to 43.3, corresponding with a change in composition from
C_{6}H_{10}O_{5} to 4C_{6}H_{10}O_{5}.H_{2}O. The partial hydrolysis
affects the whole molecule, and is limited to this effect, whereas, in
the case of celluloses of other types, there is a fractionation of the
mass, a portion undergoing a further hydrolysis to compounds of lower
molecular weight and permanently soluble. Thus in the case of the wood
celluloses the percentage recovered from solution as viscose is from 93
to 95 p.ct. It is evident that these celluloses are not homogeneous. A
similar conclusion results from the presence of furfural-yielding
compounds with the observation that the hydrolysis to soluble
derivatives mainly affects these derivatives. In the empirical
characterisation of a normal cellulose, therefore, we may include the
property of quantitative regeneration or recovery from its solution as
sulphocarbonate.

In the use of the word 'normal' as applied to a 'bleached' cotton, we
have further to show in what respects the sulphocarbonate reaction
differentiates the bleached or purified cotton cellulose from the raw
product. The following experiments may be cited: Specimens of American
and Egyptian cottons in the raw state, freed from mechanical, i.e.
non-fibrous, impurities, were treated with a mercerising alkali, and the
alkali-c