New Vegetable Colouring Matter.

Practical Magazine 17, 1876

(Chemistry applied to the Arts, Manufactures, &c.
Dyeing, Calico Printing, Bleaching, Tanning, and Allied Subjects.)

In Tahiti there is a tree of the Musaceæ family, called Musa Fehii, which grows chiefly in high places, and the fruit of which is eaten like that of the banana. In the early stages of its growth it yields a sticky, neutral juice, which in a thin layer is strawberry red, and in a thick layer blue violet. It keeps pretty well in a closed vessel, but if allowed to rest long, deposits a violet substance forming threads, and behaving like caoutchouc with solvents. The liquid, after being freed from this substance, may mix in any proportion with water and alcohol without getting thick, and then has so intense a colour that it may be diluted with five times its weight of water without any apparent weakening of its tint. Its taste is astringent, and with gelatine it gives an abundant precipitate which takes away the colour. Weak alkaline solutions make it turn to green, without producing any precipitate. Salts of lime cause an insoluble tannate precipitate, which takes away the colour. Acids make it change to a reddish colour, sulphate of iron produces a beautiful blue precipitate, and acetate of iron a blackish precipitate, like that of tannate of iron. Salts of zinc and copper colour it blue, without producing any precipitate, while acetate of lead gives a violet blue precipitate. Perchloride of tin developes a violet lake of peculiar vivacity of tone.

A trial of this new colour on yarn was made with part of the juice, freed, as stated above, from the caoutchouc substance, and diluted with five parts of water. On cotton treated with alum the liquid produced a pale violet bordering on grey, but on cotton prepared with a solution of tin the violet was very fine. The yarn, being first put into the bath of tin, and then into one of iron, and afterwards dyed, gave a deep saturated brown. On flax the same tints, but brighter, were obtained. Silk prepared with a solution of tin, and put into the dyeing-bath, took a bright grey tint.

- Polytechnisches journal.

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