DOI Page / Citation link:
https://doi.org/10.11588/diglit.62783#0044
xxxiv
OF THE COLOURS USED
Sinopia is of the colour of liver, and when prepared is a pigment
blood-red.
Cennino also appears to have well understood the difference
between these minerals. He used the Sinopia in painting, but
Armenian Bole in gilding.
Sinopia and Pabonazo, as we have observed, are ores of iron, but
Bole is classed by Phillips (Min. p. 53.) among the clays ; in the
Treatise on Mineralogy, in the Encyc. Britann. it is placed m the
Magnesian Genus. It is described as follows :—
Magnesian Genus, 2. Species Bole. Id. Kirw. I. 190. Le Bol,
Broch. I. 459. Argile Ochreuse. Haiiy. 445.—Exter. Char. Found
massive and disseminated; surface dull, sometimes a little glim-
mering ; fracture conchoidal, fragment sharp edged, colour yellowish
brown or reddish, with spots and dentritical figures of black;
opaque, rarely translucent at the edges ; very soft; easily frangible ;
adheres to the tongue; feels greasy; streak shining; sp. grav.
1.4 to 2.
Chem. Char. Before the blow-pipe it becomes black or gray,
and melts into a greenish gray slag. Falls to pieces in water with a
crackling noise, and without forming a paste. Its constituent parts
are stated by Bergman to consist of—Silica 47, Alumina 19, Mag-
nesia 6.2, Lime 5.4, Oxide of Iron 5.4, Water 17 = 100.
The chief places which yield Bole, are the Islands of Lemnos,—
hence called Lemnian earth-—Sienna in Italy, and Strigan in Silesia,
in which latter place it is deposited on indurated clay; in Upper
Lusatia, it forms nests in Basalt. Bole and similar earths were
formerly employed in medicine ; they are now only used in the prepa-
ration of colours.—Encyc. Brit. Tit. Mineralogy.
I consider that it may be collected from the above extracts, that
Sinopia is that species of Red Iron Ore called red ochre by Phillips
and other mineralogists. This mineral will require the same prepara-
tion as a pigment as other earths ; namely, careful washing and
grinding.
BLUE COLOURS.
Palomino was right when he said that blue pigments were the Scylla
of fresco painting. He had doubtless seen many instances of their
OF THE COLOURS USED
Sinopia is of the colour of liver, and when prepared is a pigment
blood-red.
Cennino also appears to have well understood the difference
between these minerals. He used the Sinopia in painting, but
Armenian Bole in gilding.
Sinopia and Pabonazo, as we have observed, are ores of iron, but
Bole is classed by Phillips (Min. p. 53.) among the clays ; in the
Treatise on Mineralogy, in the Encyc. Britann. it is placed m the
Magnesian Genus. It is described as follows :—
Magnesian Genus, 2. Species Bole. Id. Kirw. I. 190. Le Bol,
Broch. I. 459. Argile Ochreuse. Haiiy. 445.—Exter. Char. Found
massive and disseminated; surface dull, sometimes a little glim-
mering ; fracture conchoidal, fragment sharp edged, colour yellowish
brown or reddish, with spots and dentritical figures of black;
opaque, rarely translucent at the edges ; very soft; easily frangible ;
adheres to the tongue; feels greasy; streak shining; sp. grav.
1.4 to 2.
Chem. Char. Before the blow-pipe it becomes black or gray,
and melts into a greenish gray slag. Falls to pieces in water with a
crackling noise, and without forming a paste. Its constituent parts
are stated by Bergman to consist of—Silica 47, Alumina 19, Mag-
nesia 6.2, Lime 5.4, Oxide of Iron 5.4, Water 17 = 100.
The chief places which yield Bole, are the Islands of Lemnos,—
hence called Lemnian earth-—Sienna in Italy, and Strigan in Silesia,
in which latter place it is deposited on indurated clay; in Upper
Lusatia, it forms nests in Basalt. Bole and similar earths were
formerly employed in medicine ; they are now only used in the prepa-
ration of colours.—Encyc. Brit. Tit. Mineralogy.
I consider that it may be collected from the above extracts, that
Sinopia is that species of Red Iron Ore called red ochre by Phillips
and other mineralogists. This mineral will require the same prepara-
tion as a pigment as other earths ; namely, careful washing and
grinding.
BLUE COLOURS.
Palomino was right when he said that blue pigments were the Scylla
of fresco painting. He had doubtless seen many instances of their