Page:Indian Medicinal Plants (Text Part 2).djvu/192

942 hydrates causes it to assume immediately a cherry-red colour, which quickly passes into brick-red and olive-green.

Owing to the insolubility of the crystals in water a proof spirit solution was used in applying the following tests : —

1. A solution of silver nitrate in proof spirit produced a bluish-black colour immediately, and after the liquid had stood for a few minutes black particles of reduced silver were precipitated.

2. A solution of neutral acetate of lead in proof spirit gave a light-red bulky precipitate insoluble in boiling acetic acid.

3. Lime water imparted an orange colour, which quickly changed to olive-green, followed by a precipitate of the same colour.

4. An aqueous solution of copper gave a golden yellow colour, quickly followed by a dirty brown precipitate, the supernatant liquid being distinctly greenish.

5. Solution of ferric chloride (acid) produced a brownish-red colour, which, in a few minutes, turned smoke-colour.

6. Solution of subacetate of lead gave a golden yellow precipitate.

7. An aqueous solution of mercuric chloride produced a white precipitate.

8. An aqueous solution of permanganate of potash, acidified with sulphuric acid, was instantly decolorized.

9. A solution of the crystals in proof spirit did not reduce Fehling.

The authors say : — " We have attempted to hydrolyse this body, by subjecting a strong alcoholic solution to the prolonged action of 10 per cent, solution of sulphuric acid at a boiling temperature, but without success.

" We have also inquired into its nature and centesimal composition, but the results so far obtained are not sufficiently conclusive to be incorporated in this paper. We hope to be able to publish shortly a supplementary note dealing with points in process of investigation. Mean while, we propose that this interesting principle be designated Oroxylin."

C. The marc left after exhaustion with petroleum spirit and ether was percolated with cold absolute alcohol. The residue resulting from the distillation of the spirit was treated with cold proof spirit, which took up the greater part of it. The insoluble portion dissolved readily in boiling proof spirit, and, on examination proved to be largely composed of the yellow crystalline body oroxylin. The cold proof spirit solution of the alcoholic residue was evaporated to dryness and the extract treated with water and filtered. The filtrate was treated successively with neutral and basic acetate of lead, and the precipitates after washing were suspended in water, decomposed by a current of sulphuretted hydrogen and the resultant plumbic sulphide removed by filtration. Sulphuretted hydrogen was also passed through the filtrate from the basic or plumbic acetate and the precipitated lead sulphide removed by filtration.

The three liquids thus obtained, which for convenience may be denominated i., ii., iii., were then evaporated down and the respective residues examined.

(i.) It was dissolved in the smallest quantity possible of cold water and diluted with many times its volume of alcohol. After setting aside for