to _Neronias_, but this name
endured but a short while. Titus here exhibited gladiatorial shows to
celebrate the capture of Jerusalem. The Crusaders took the city in 1130,
and lost it to the Moslems in 1165. Banias is a poor village inhabited by
about 350 Moslems; all round it are gardens of fruit-trees. It is well
watered and fertile. There are not many remains of the Roman city above
ground. The Crusaders' castle of Subeibeh, one of the finest in Palestine,
occupies the summit of a conical hill above the village.

(R. A. S. M.)

CAESIUM (symbol Cs, atomic weight 132.9), one of the alkali metals. Its
name is derived from the Lat. _caesius_, sky-blue, from two bright blue
lines of its spectrum. It is of historical importance, since it was the
first metal to be discovered by the aid of the spectroscope (R. Bunsen,
_Berlin Acad. Ber._, 1860), although caesium salts had undoubtedly been
examined before, but had been mistaken for potassium salts (see C.F.
Plattner, _Pog. Ann._, 1846, p. 443, on the analysis of pollux and the
subsequent work of F. Pisani, _Comptes Rendus_, 1864, 58, p. 714). Caesium
is found in the mineral springs of Frankenhausen, Montecatini, di Val di
Nievole, Tuscany, and Wheal Clifford near Redruth, Cornwall (W.A. Miller,
_Chem. News_, 1864, 10, p. 181), and, associated with rubidium, at
Duerkheim; it is also found in lepidolite, leucite, petalite, triphylline
and in the carnallite from Stassfurt. The separation of caesium from the
minerals which contain it is an exceedingly difficult and laborious
process. According to R. Bunsen, the best source of rubidium and caesium
salts is the residue left after extraction of lithium salts from
lepidolite. This residue consists of sodium, potassium and lithium
chlorides, with small quantities of caesium and rubidium chlorides. The
caesium and rubidium are separated from this by repeated fractional
crystallization of their double platinum chlorides, which are much less
soluble in water than those of the other alkali metals (R. Bunsen, _Ann._,
1862, 122, p. 347; 1863, 125, p. 367). The platino-chlorides are reduced by
hydrogen, and the caesium and rubidium chlorides extracted by water. See
also A. Schroetter (_Jour. prak. Chem._, 1864, 93, p. 2075) and W. Heintz
(_Journ. prak. Chem._, 1862, 87, p. 310). W. Feit and K. Kubierschky
(_Chem. Zeit._, 1892, 16, p. 335) separate rubidium and caesium from the
other alkali metals by converting them into double chlorides wit