CHLOROPHYL.

437

aftion of acids the green colour is rapidly restored. The yellow leaves whichfall in autumn contain phylloxanthin only, and their alcoholic extradt doesnot yield—when treated with the above-named mixture of hydrochloric acidand ether—the characteristic phenomenon: the cause, therefore, of theautumnal change of the leaves is the fact that while the phylloxanthin—arather stable compound—remains, the phyllocyanin is oxidised and completelydecomposed. We mention these facts here because they give a clue to thefailures of chlorophyl as a dye-ware.

It may interest our readers to learn what kind of attempts have beenmade, especially by M. Verdeil, to fix the green colouring matter ofplants to woven textile fibres. He extracts from the fleshy parts of the im-mature flower-buds of the thistle and artichoke a green-coloured pigment,apparently different from chlorophyl as well as from lo-kao. The juicesqueezed from the buds is originally colourless, but by the action of air andthe addition of carbonate of soda it assumes a greenish-yellow, which is con-verted into a bluish-green after neutralising with acetic acid. The colouringmatter is next precipitated by acetate of lead, and the ensuing precipitate isdecomposed by means of sulphuric acid diluted with alcohol, and kept at atemperature of 40°. The alcoholic solution becomes yellowish-brown ; thesulphate of lead having been removed by filtration, the colouring matter isprecipitated by the addition of ether, and the precipitate, having been colledtedon a filter, is first washed with ether and next with water. The substancethus obtained is insoluble in water, ether, and acids, but soluble in alcoholand alkalies, forming, with the oxides of aluminium and tin, deep green lakes,which resist the a&ion of light, and might be applied for the purposes ofprinting on tissues, as well as for artists’ colours. The green is not, however,particularly beautiful.

M. Hartmann* has experimented for the purpose of applying the chlorophylof grass to woven fabrics. This chlorophyl is prepared in the followingmanner;—The grass is first washed with warm and slightly alkaline water,and then steeped for twenty-fours in a caustic soda-lye of sp. gr. 1-070, con-taining about 7-75 percent of dry caustic soda; the deeply coloured fluid isdecanted, and next precipitated with hydrochloric acid, yielding a flocculentgreen matter, which is colledted upon a filter and washed. The quantity of chloro-phyl thus prepared is far from abundant, being only 1 part for 100 parts ofgrass. The pigment, suitably thickened with gum, to which lime-water orammonia is added, yields, when printed and steamed, colours which—althoughnot exadtly beautiful—are fast, and prove, moreover, that chlorophyl may befixed on woven fabrics.

M. Cordillot prefers the following process:—Grass is first exhausted by boilingwater, and next treated with a very weak caustic soda solution (sp. gr. 1-013),which also contains some phosphates of alumina and lime ; the previouslydecanted green liquid is neutralised with hydrochloric acid, whereby a greenflocculent matter—a lake of chlorophyl—is thrown down.

For the purpose of printing the author takes 250 grms. of a caustic sodasolution, sp. gr. 1-333, containing about 31-2 per cent of dry caustic soda to1 kilo, of the moist pasty lake: this solution has a specific gravity = 1-070.too kilos, of grass yield about 8 litres of the pasty lake, which, after having

* " Bulletins de la Societe Industrieile de Mulhouse,” xxvi., 283.