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RAYS OF POSITIVE ELECTRICITY.

THE positive rays were discovered by Goldstein in I886.¹His apparatus is represented in Fig. I ; the cathode K which
stretched right across the tube r was a metal plate through
which a number of holes were drilled, the diameter of the holes
being considerably less than the thickness of the plate; the axes
of the holes were at right angles to the surface of the plate;
the anode a was at the end of the lower part of the tube.
The pressure of the gas in the tube was so low that when the
electrodes K and a were connected with the terminals of an
induction coil and a discharge passed through the tube, the
dark space below the cathode was well developed. Under
these circumstances Goldstein found that slightly diverging
bundles of a luminous discharge streamed through the holes
in the cathode into the upper tube. The colour of the light in
these bundles depended on the kind of gas with which the
tube was filled: when it was air the light was yellowish, when
it was hydrogen, rose colour. These rays can be shown very
conveniently by the use of the tube represented in Fig. 2 ; a
form also used by Goldstein in his earlier experiments. The
cathode which fills the middle of the tube is a flat disc with
a hole in It; a metal tube fitting into the hole is soldered

¹ Uber eine nocb nicht untersuchte Strahlungsform an der Kathode indu-
cirter Entladungen. "Berl. Ber.₉" xxxix, p. 691, 1886; " Wied. Ann.," LXIV,
p. 38, 1898.



	RAYS OF POSITIVE ELECTRICITY. THE positive rays were discovered by Goldstein in I886.¹His apparatus is represented in Fig. I ; the cathode K which stretched right across the tube r was a metal plate through which a number of holes were drilled, the diameter of the holes being considerably less than the thickness of the plate; the axes of the holes were at right angles to the surface of the plate; the anode a was at the end of the lower part of the tube. The pressure of the gas in the tube was so low that when the electrodes K and a were connected with the terminals of an induction coil and a discharge passed through the tube, the dark space below the cathode was well developed. Under these circumstances Goldstein found that slightly diverging bundles of a luminous discharge streamed through the holes in the cathode into the upper tube. The colour of the light in these bundles depended on the kind of gas with which the tube was filled: when it was air the light was yellowish, when it was hydrogen, rose colour. These rays can be shown very conveniently by the use of the tube represented in Fig. 2 ; a form also used by Goldstein in his earlier experiments. The cathode which fills the middle of the tube is a flat disc with a hole in It; a metal tube fitting into the hole is soldered ¹ Uber eine nocb nicht untersuchte Strahlungsform an der Kathode indu- cirter Entladungen. "Berl. Ber.₉" xxxix, p. 691, 1886; " Wied. Ann.," LXIV, p. 38, 1898. I