is seen to be more regular in outline, and
a round, pseudo-tubular form prevails, due to the conditions of
shrinkage and collapse of the fibre in parting with the solvents, and in
then dehydrating. The constants for 'breaking strain,' both in the
original and moistened condition, for elasticity, &c., are closely
approximate to those for the Chardonnet product.

_Pauly 'silk'._--The form of the ultimate fibres is much more regular
and the contour of the cross-section is smooth. The product shows more
resistance to moisture and to alkaline solutions.

_Viscose 'silk'_ is referred to in terms of a communication appearing in
'Papier-Zeitung,' 1898, 2416.

In the above section the following publications are referred
to: Chardonnet, 'Compt. rend.,' 1887, 105, 900; and 1889, 108,
962; Silbermann, 'Die Seide,' 1897, v. 2, 143; Herzog,
'Farber-Zeitung,' 1894/5, 49-50; Thiele, ibid. 1897, 133; O.
Schlesinger, 'Papier-Zeitung,' 1895, 1578-81, 1610-12.

_Action of Reagents upon Natural and Artificial Silks._

1. _Potassium hydrate_ in solution of maximum concentration dissolves
the silks proper, (a) China silk on slight warming, (b) Tussah silk
on boiling. The cellulose 'silks' show swelling with discolouration, but
the fibrous character is not destroyed even on boiling.

2. _Potassium hydrate_ 40 p.ct. China silk dissolves completely at
65 deg.-85 deg.; Tussah silk swells considerably at 75 deg. and dissolves at
100 deg.-120 deg.. The cellulose 'silks' are attacked with discolouration; at
140 deg. (boiling-point of the solution) there is progressive solvent
action, but the action is incomplete. The Pauly product is most
resistant.

3. _Zinc chloride_, 40 p.ct. solution. Both the natural silks and
lustra-celluloses are attacked at 100 deg., and on raising the temperature
the further actions are as follows: China silk is completely dissolved
at 110-120 deg.; Tussah silk at 130-135 deg.; the collodion products at
140-145 deg.; the Pauly product was again most resistant, dissolving at
180 deg..

4. _Alkaline cupric oxide_ (glycerin) solution was prepared by
dissolving 10 grs. of the sulphate in 100 c.c. water, adding 5 grs.
glycerin and 10 c.c. of 40 p.ct. KOH. In this solution the China silk
dissolved at the ordinary temperature; Tussah silk and the
lustra-celluloses were not appreciably affected.

5. _Cuprammonium solution_ was prepared by dissolving the precipitated
cupric hydrate in 24 p.ct.