g atoms,
the electric force not causing, but merely directing, the interchange.
This view found little favour until 1887, when it was taken up by S.A.
Arrhenius, who made it the basis of the theory of electrolytic
dissociation. In addition to many scientific papers he wrote _Die
Potentialfunktion und das Potential_, 1864, and _Abhandlungen ueber die
mechanische Waermetheorie_, 1864-1867.

CLAUSTHAL, or KLAUSTHAL, a town of Germany, in the Prussian Harz, lying
on a bleak plateau, 1860 ft. above sea-level, 50. m. by rail W.S.W. of
Halberstadt. Pop. (1905) 8565. Clausthal is the chief mining town of the
Upper Harz Mountains, and practically forms one town with Zellerfeld,
which is separated from it by a small stream, the Zellbach. The streets
are broad, opportunity for improvement having been given by fires in
1844 and 1854; the houses are mostly of wood. There are an Evangelical
and a Roman Catholic church, and a gymnasium. Clausthal has a famous
mining college with a mineralogical museum, and a disused mint. Its
chief mines are silver and lead, but it also smelts copper and a little
gold. Four or five sanatoria are in the neighbourhood. The museum of the
Upper Harz is at Zellerfeld.

Clausthal was founded about the middle of the 12th century in
consequence probably of the erection of a Benedictine monastery (closed
in 1431), remains of which still exist in Zellerfeld. At the beginning
of the 16th century the dukes of Brunswick made a new settlement here,
and under their directions the mining, which had been begun by the
monks, was carried on more energetically. The first church was built at
Clausthal in 1570. In 1864 the control of the mines passed into the
hands of the state.

CLAVECIN, the French for clavisymbal or harpsichord (Ger. _Clavicymbel_
or _Dockenklavier_), an abbreviation of the Flemish _clavisinbal_ and
Ital. _clavicimbalo_, a keyboard musical instrument in which the strings
were plucked by means of a plectrum consisting of a quill mounted upon a
jack.

See PIANOFORTE; HARPSICHORD.

CLAVICEMBALO, or GRAVICEMBALO (from Lat. _clavis_, key, and _cymbalum_,
cymbal; Eng. clavicymbal, clavisymbal; Flemish, _clavisinbal_; Span.
_clavisinbanos_), a keyboard musical instrument with strings plucked by
means of small quill or leather plectra. "Cymbal" (Gr. [Greek:
kumbalon], from [Greek: khumbe], a hollow vessel) was the old European
term for the dulcimer, and hence its place in the formation