CXIV
§ 286. b) Luminous effects. By bringing the two elec
trodes very nearly in contact the sparks follow each other with
such rapidity that a continuous light is produced; if two pieces
of charcoal are connected with the poles, the electric light is
most brilliant. The illuminating power of this light is equal to
that of 572 candles; even the coal-gas flame is thrown into the
shade in this light; but if too strong, it produces pain in the eye
and may even cause something like sun-stroke. By this power
ful light also the Photo-electric microscope (Fig. No. XXIX) is
illuminated. The rays of the electric light pass through a
system of lenses (just as in the solar microscope, see § 207 and
an extremely magnified image, even of the smallest object (the
animalculae in water) will be produced on a wall or on a white
screen.
§ 287. (c) Magnetic Effects. If an electric stream is led
spirally round a rod of iron, the iron shows magnetic attraction.
III. Chemical effects.
§ a) Substances are decomposed and the elements
transported if they are traversed, by an electric current. Thus
water may be decomposed into Hydrogen and Oxygen, (disco
vered by Carlisle and Nicholson 1800), and the existence of
Potassium and Sodium was discovered by a voltaic current
(Davy 1807). 443. Oxides are decomposed in such a manner
that Oxygen appears at the positive pole, the radical at the
negative; as to salts the acid appears at the positive pole, the
alkali at the negative.
§ 289. An application of this electrical effect we see also
in the art of Galvanoplastics, by which by means of a galva
nic current the reproduction of any object is effected, because
this current decomposes a metal and deposits on it an impression
