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. ammonia. In this reagent also the China silk dissolved, and the Tussah silk as well as the lustra-celluloses underwent no appreciable change. 6. _An ammoniacal solution of nickel oxide_ was prepared by dissolving the precipitated hydrated oxide in concentrated ammonia. The China silk was dissolved by this reagent; Tussah silk and the lustra-celluloses entirely resisted its action. 7. _Fehling's solution_ is a solvent of the natural silks, but is without action on the lustra-celluloses. 8. _Chromic acid_--20 p.ct. CrO_{3}--solution dissolves both the natural silks and the lustra-celluloses at the boiling temperature of the solution. 9. _Millon's reagent_, at the boiling solution, colours the natural silks violet: the lustra-celluloses give no reaction. 10. _Concentrated nitric acid_ attacks the natural silks powerfully in the cold; the lustra-celluloses dissolve on heating. 11. _Iodine solution_ (I in KI) colours the China silk a deep brown, Tussah a pale brown; the celluloses from collodion are coloured at first brown, then blue. The Pauly product, on the other hand, does not react.