Fierz-David, H. E. (Hans Eduard), 1882-1953 · New York, D. Van Nostrand · leaf 151
112 DYES formic acid), and the alkali is replaced by acetate or formate. In very rare cases no addition is necessary, as the coupling takes place spontaneously with elimination of mineral acid. Certain amines insoluble in water, such as diphenylamine, cresidine, a-naphthyl- … FiG. 21. — Calibrated vessel for coupling. amine, etc., are sometimes coupled in alcoholic solution (c/. Tropzeolin). The pot illustrated above (Fig. 21) is specially suited for coupling. The rough graduation makes it easier to estimate the quantity of fluid present.
Dyes and dyeing
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