The influence of Acids in Dyeing with Madder and its Artificial Substitutes.

Practical Magazine 17, 1876

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

In a paper on this subject, communicated to the "Bulletin de la Société Industrielle de Mulhouse," M. Rosenstrehl, shows that alizarine and the colours related to it deprive carbonic and acetic acids of their salts, so as to form lakes with simple bases which are themselves decomposed by the same acids. In presence of the oxides of aluminium and iron this deprival is more complete, and extends even to salts with energetic base, such as the nitrates and chloride of calcium. There are then formed lakes with double base.

He also shows the important part which carbonic acid, naturally dissolved in water, performs in the operation of dyeing, indicates the cause of the divergences that exist between the results of experiments in the laboratory and those of industrial operations, and suggests means of putting an end to the disagreement. He proposes the substitution of acetate of calcium for the carbonate, as being more advantageous, and incidentally mentions the peculiar dissolving action which acetate of sodium exercises when hot on the colouring materials of which he has treated.

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