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.

12. _Diphenylamine sulphate._--A solution of the base in concentrated
sulphuric acid colours the natural silks a brown; the collodion 'silks'
give a strong blue reaction due to the presence of residual
nitro-groups. The Pauly product is not affected.

13. _Brucin sulphate_ in presence of concentrated sulphuric acid colours
the natural silks only slightly (brown); the collodion 'silks' give a
strong red colouration. The Pauly product again is without reaction.

14. _Water._--The natural silks do not soften in the mouth as do the
lustra-celluloses.

15. _Water of condition_ was determined by drying at 100 deg.; the following
percentages resulted (a). The percentages of water (b) taken up from
the atmosphere after forty-three hours' exposure were:

(a) (b)
China (raw) silk 7.97 2.24
Tussah silk 8.26 5.00

Lustra-celluloses:

Chardonnet (Besancon) 10.37 5.64
" Spreitenbach 11.17 5.77
Lehner 10.71 5.97
Pauly 10.04 6.94

16. _Behaviour on heating at 200 deg.._--After two hours' heating at this
temperature the following changes were noted:

China silk Much discoloured (brown).
Tussah silk Scarcely affec