Harper's new monthly magazine, 41 / 1870
A note of alarm has been raised in regard to the employment of aniline dyes for coloring various liquids and fruit sirups, used extensively as beverages; and the dangerous effects likely to result from the use of such mixtures are carefully pointed out. The following are some of the methods of distinguishing between the true fruit juices and those that have been colored by any of the aniline dyes.
Genuine fruit sirups become completely deprived of their color by means of chlorine; and while aniline colors are also destroyed, a black deposit is left, which is readily recognized. Sulphuric acid, nitric acid, and hydrochloric acid render the red colors of genuine sirups brighter, and color the artificial of a yellowish orange. Caustic potash decolorizes fuchsine sirups, and changes the red fruit sirups into a dirty green. Carbonate of potash does not alter the color of artificial sirups, but changes the genuine to green. Acetate of lead produces a greenish deposit in a genuine fruit sirup, and a red one in fuchsine sirup. A similar change takes place in the gradual addition of alum and carbonate of potash. Aldehyde changes sirups colored with aniline to blue.