With Cobalt Blue The Name Azure Has Sometimes Been Given To It
:
ON THE PRIMARY, BLUE.
Varying exceedingly in quality and colour, the rougher kinds have been
employed by the laundress, and in the making of porcelain, pottery,
stained glass, encaustic tiles, &c.; as well as to cover the yellow
tinge of paper. For this last purpose, however, smalt is not perfectly
adapted, the colour being difficult to lay on uniformly, and the paper
when written on blunting the nibs of pens. Hence it has been superseded
to a great extent by artificial ultramarine, the presence of which may
be detected by the yellow spot which a drop of acid leaves on the paper.