The solution of cellulose by Schweitzer’s reagent is undoubtedly a chemical action. Cellulose is to be regarded as a polyhydric alcohol, with one or several atoms of hydrogen of the hydroxyl groups replaceable by metals. According to Piest (_loc. cit._) a ‘Cupramine base’ is formed by the replacement of this hydrogen by copper and the amino-group, NH₂. The action of sodium hydroxide on cellulose, however, is generally regarded rather as an additive reaction, the product, ‘alkali cellulose,’ being usually written C₆H₁₀O₅,NaOH. A careful chemical investigation alone can reveal the actual nature of the compound formed; such an investigation, apart from its scientific interest, might yield results of considerable technical importance. ~The Viscose Process.~--Shortly after the introduction of the Chardonnet process, patents were taken out which protected a very cheap and simple method of dissolving cellulose,[529] which had been discovered by two well-known English authorities. Cross and Bevan. They found that mercerisation, _i.e._ the action of the sodium hydroxide on cellulose, produces a swollen, transparent mass, which very readily takes up carbon disulphide. When exposed to the action of this liquid for three or four hours, at ordinary temperatures, the mass swells further, gelatinising and becoming soluble in water. On treatment with water, a yellowish, extremely slimy solution is obtained, from which cellulose is precipitated on prolonged standing, by heating, or by oxidation. The substance is apparently a cellulose xanthate, and may be written NaS·CS·O·C₆H₉O₄,NaOH.[530] On account of the extremely viscous nature of the aqueous solution, Cross and Bevan gave it the name Viscoid. [529] _Vide_, _e.g._ Cross, Bevan, and Beadle, _D. R. P._ 70999, granted September, 1893. [530] _Vide_ Beltzer, _Zeitsch. angew. Chem._ 1908, ~21~, 1731. During the last few years this method of dissolving cellulose has been employed in the manufacture of artificial silk, under the name ‘Viscose Process.’ The product obtained is very suitable for the manufacture of incandescent mantles, and is considerably cheaper than either the Chardonnet or Pauly silk.