e preliminary mercerising
treatment and placing the alkali cellulose in contact with copper and
ammonia. (All reagents employed in molecular proportions.) The author
notes that the so-called hydrocellulose (Girard) (5) is almost insoluble
in cuprammonium, as is starch. It is rendered soluble by alkali
treatment.

GROUP 3. _Lustra-cellulose_ prepared by spinning a solution of cellulose
in concentrated chloride of zinc.

This solution has been known for a long time and used for making
filaments for incandescent lamps. The cellulose threads, however, have
very little tenacity. This is no doubt due to the conditions necessary
for forming the solution, the prolonged digestion causing powerful
hydrolysis (1). Neither the process of Wynne and Powell (2) nor that of
Dreaper and Tompkins (3), who have endeavoured to bring the matter to a
practical issue, are calculated to produce a thread taking a place as a
textile. The author has described in his American patent (4) a method of
effecting the solution in the cold, viz. again by first mercerising the
cellulose and washing away the caustic soda. This product dissolves in
the cold and the solution remains unaltered if kept at low temperature.
Experiments are being continued with these modifications of the process,
and the author anticipates successful results. The modifications having
the effect of maintaining the high molecular weight of the cellulose, it
would appear that these investigations confirm the theory of Cross and
Bevan that the tenacity of a film or thread of structureless regenerated
cellulose is directly proportional to the molecular weight of the
cellulose, i.e. to its degree of molecular aggregation (5).

GROUP 4. 'Viscose' silks obtained by spinning solutions of xanthate of
cellulose.

In 1892, Cross and Bevan patented the preparation of a new and curious
compound of cellulose, the thiocarbonate (1) (2) (3). Great hopes were
based upon this product at the time of its discovery. It was expected
to yield a considerable industrial and financial profit and also to
contribute to the scientific study of cellulose. The later patents of C.
H. Stearn (4) describe the application of viscose to the spinning of
artificial silk. The viscose is projected into solutions of chloride of
ammonium and washed in a succession of saline solutions to remove the
residual sulphur impurities. The author remarks that though it has a
certain interest to have succeeded in making a thread