d H. Thiele (_Zeit. f. anorg. Chem_., 1896,
II, p. 73), by reducing cobalto-cobaltic oxide, and by the analysis of
the chloride, have obtained the values 58.56 and 58.48. G. P. Baxter
and others deduced the value 58.995 (O = 16).

Cobalt salts may be readily detected by the formation of the black
sulphide, in alkaline solution, and by the blue colour they produce
when fused with borax. For the quantitative determination of cobalt,
it is either weighed as the oxide, Co3O4, obtained by ignition of the
precipitated monoxide, or it is reduced in a current of hydrogen and
weighed as metal. For the quantitative separation of cobalt and
nickel, see E. Hintz (_Zeit. f. anal. Chem._, 1891, 30, p. 227), and
also NICKEL.

COBALTITE, a mineral with the composition CoAsS, cobalt sulpharsenide.
It is found as granular to compact masses, and frequently as beautifully
developed crystals, which have the same symmetry as the isomorphous
mineral pyrites, being cubic with parallel hemihedrism. The usual forms
are the cube, octahedron and pentagonal dodecahedron {210}. The colour is
silver-white with a reddish tinge, and the lustre brilliant and
metallic, hence the old name cobalt-glance; the streak is greyish-black.
The mineral is brittle, and possesses distinct cleavages parallel to the
faces of the cube; hardness 5-1/2; specific gravity 6.2. The brilliant
crystals from Tunaberg in Sodermanland and Hakansboda in Vestmanland,
Sweden, and from Skutterud near Drammen in Norway are well known in
mineral collections. The cobalt ores at these localities occur with
pyrites and chalcopyrite as bands in gneiss. Crystals have also been
found at Khetri in Rajputana, and under the name _sehta_ the mineral is
used by Indian jewellers for producing a blue enamel on gold and silver
ornaments. Massive cobaltite has been found in small amount in the
Botallack mine, Cornwall. A variety containing much iron replacing
cobalt, and known as ferrocobaltite (Ger. _Stahlkobalt_), occurs at
Siegen in Westphalia. (L. J. S.)

COBAN, or SANTO DOMINGO DE COBAN, the capital of the department of Alta
Vera Paz in central Guatemala; about 90 m. N. of the city of Guatemala,
on the Cojabon, a left-hand tributary of the Polochic. Pop. (1905) about
31,000. The town is built in a mountainous and fertile district, and
consists chiefly of adobe Indian cottages, surrounded by gardens of
flowering shrubs. More modern houses have been erected