HCl = COS + KCl + C2H5OH. It is
a colourless, odourless gas, which burns with a blue flame and is
decomposed by heat. Its vapour density is 2.1046 (air = 1). The
liquefied gas boils at -47 deg. C. under atmospheric pressure. It is
soluble in water; the aqueous solution gradually decomposes on
standing, forming carbon dioxide and sulphuretted hydrogen. It is
easily soluble in solutions of the caustic alkalis, provided they are
not too concentrated, forming solutions of alkaline carbonates and
sulphides, COS + 4KHO = K2CO3 + K2S + 2H2O.

CARBONADO, a name given in Brazil to a dark massive form of impure
diamond, known also as "carbonate" and in trade simply as carbon. It is
sometimes called black diamond. Generally it is found in small masses of
irregular polyhedral form, black, brown or dark-grey in colour, with a
dull resinoid lustre; and breaking with a granular fracture, paler in
colour, and in some cases much resembling that of fine-grained steel.
Being slightly cellular, its specific gravity is rather less than that
of crystallized diamond. It is found almost exclusively in the state of
Bahia in Brazil, where it occurs in the _cascalho_ or diamond-bearing
gravel. Borneo also yields it in small quantity. Formerly of little or
no value, it came into use on the introduction of Leschot's
diamond-drills, and is now extremely valuable for mounting in the steel
crowns used for diamond-boring. Having no cleavage, the carbon is less
liable to fracture on the rotation of the drill than is crystallized
diamond. The largest piece of carbonado ever recorded was found in Bahia
in 1895, and weighed 3150 carats. Pieces of large size are, however,
relatively less valuable than those of moderate dimensions, since they
require the expenditure of much labour in reducing them to fragments of
a suitable size for mounting in the drill-heads. Ilmenite has sometimes
been mistaken in the South African mines for carbonado. (F. W. R.*)

CARBONARI (an Italian word meaning "charcoal-burners"), the name of
certain secret societies of a revolutionary tendency which played an
active part in the history of Italy and France early in the 19th
century. Societies of a similar nature had existed in other countries
and epochs, but the stories of the derivation of the Carbonari from
mysterious brotherhoods of the middle ages are purely fantastic. The
Carbonari were probably an offshoot of the Freemasons, from whom they
dif