Significats de blue coloration en anglès

This is based on the blue coloration of ammoniacal copper solutions.

Add concentrated ammonia drop by drop until the appearance of a deep blue coloration indicates an excess.

Apply a warm sample of a slightly acid solution of yellow prussiate of potash; iron rust will be indicated by a blue coloration.

The electrolysed solution should be treated with an excess of ammonia, when a blue coloration will indicate copper, in which case the electrolysis is unsatisfactory.