iation is occasioned by
differences in chemical constitution of these various cottons. The
influence of the chemical factors is also emphasised by the increased
dyeing capacity of the mercerised goods, which effect, moreover, is
independent of those conditions of strain or tension under mercerisation
which determine lustre. It is found in effect that with a varied range
of dye stuffs a given shade is produced with from 10 to 30 p.ct. less
colouring matter than is required for the ordinary, i.e. unmercerised,
goods.

In reference to the constants of strength and elasticity, Buntrock gives
the following results of observations upon a 40^{5} twofold yarn, five
threads of 50 cm. length being taken for each test(Prometheus, 1897, p.
690): (a) the original yarn broke under a load of 1440 grms.; (b)
after mercerisation without tension the load required was 2420 grms.;
(c) after mercerisation under strain, 1950 grms. Mercerisation,
therefore, increases the strength of the yarn from 30 to 66 p.ct., the
increase being lessened proportionately to the strain accompanying
mercerisation. _Elasticity_, as measured by the extension under the
breaking load, remains about the same in yarns mercerised under strain,
but when allowed to shrink under mercerisation there is an increase of
30-40 p.ct. over the original.

The _change of form_ sustained by the individual fibres has been studied
by H. Lange [Farberzeitung, 1898, 197-198], whose microphotographs of
the cotton fibres, both in length and cross-section, are reproduced. In
general terms, the change is from the flattened riband of the original
fibre to a cylindrical tube with much diminished and rounded central
canal. The effect of strain under mercerisation is chiefly seen in the
contour of the surface, which is smooth, and the obliteration at
intervals of the canal. Hence the increased transparency and more
complete reflection of the light from the surface, and the consequent
approximation to the optical properties of the silk fibre.

The work concludes with a section devoted to a description of the
various practical systems of mercerisation of yarns in general practice
in Germany, and an account of the methods adopted in dyeing the
mercerised yarns.

RESEARCHES ON MERCERISED COTTON.

A. FRAENKEL and P. FRIEDLAENDER (Mitt. k.-k. Techn. Gew. Mus., Wien,
1898, 326).

The authors, after investigation, are inclined to attribute the lustre
of mercerised cotton to the absence of