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°-85°; Tussah silk swells considerably at 75° and dissolves at 100°-120°. The cellulose 'silks' are attacked with discolouration; at 140° (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°, and on raising the temperature the further actions are as follows: China silk is completely dissolved at 110-120°; Tussah silk at 130-135°; the collodion products at 140-145°; the Pauly product was again most resistant, dissolving at 180°.
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. CrO3—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.