Merrifield, Mary P.: The art of fresco painting, as practised by the old Italian and Spanish masters, with a preliminary inquiry into the nature of the colours used in fresco painting: with observations and notes (London: Charles Gilpin, 1846)

IN FRESCO PAINTING.

xlii

cobalt could be used as a pigment; he describes (p. 466) three kinds,
differing principally in colour ; the first was black, the second grey,
and the third the colour of iron. He says that cobalt corrodes and
consumes the hands and feet of those who work it, if they are not
careful to defend themselves from it. Matthioli, (Comm, on Diosc.
p. 1395) observes, that “ Kobolt is a corrosive substance, that fre-
quently ulcerates the hands and feet of those who dig it, nor is this
to be wondered at, since it kills like deadly poison.” He adds, that
in Bohemia it is used to kill flies, but he says nothing of its being
used as a pigment. The art of purifying and preparing cobalt as a
pigment, is of comparatively modern invention, at least in Europe,
and it is extremely probable, indeed almost certain, that it was used
in the form of Zaffre as a pigment, long before the art of preparing
a pigment of a pure blue colour from it was known ; Zaffre not being
a pure blue, but inclining to red. It appears also, that the process
described by Cennino (chap. 60) for preparing Azzurro della Magna
for use, is not applicable to the mineral cobalt, which requires
chemical preparation before it can be used as a pigment; for we
have seen that the natural colours of this mineral are black, grey,
and the colour of iron, and not blue. The simple process of grinding
and washing it with water, would not be sufficient to develope the
blue colour of cobalt; if it were, it is quite clear, the long and trou-
blesome processes, now in use for purifying this mineral, are unne-
cessary ; besides, if cobalt required chemical preparation, it could
scarcely be included with propriety in Cennino’s list of natural
pigments. (See Cenn. chap. 60, and for the modern method of
purifying cobalt, see Ure’s Diet, of Chemistry and Mineralogy,
Chaptal’s Chimie appliquee aux Arts, M. de Brongniart’s Traite
des Arts Ceramiques, Merimee, De la peinture a 1’huile, Marcucci
Saggio Analitico dei Colori, &c.)
The ancients possessed some -native blue and green pigments, to
which they gave the names of Chrysocola, Lapis Armenus, Coeruleum,
and Cyaneum, (see Pliny, Lib. xxxv. Chap. 6). The first is green,
the second greenish-blue or blue, the third and fourth blue. Geo.
Agricola, Matthioli, and Laguna, mention pigments of the same
name. All agree in the general description, but vary in their account
of the colour. They also agree in stating that they were found in
d