RAYS OF POSITIVE ELECTRICITYThe positive rays were discovered by Goldstein in 1886.1 His apparatus is represented in Fig. 1 ; 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 iTable of Contents CONTENTS; PACK; Rays of Positive Electricity i; Rectilinear Propagation of the Positive Rays 5; Double and Hollow Cathodes 5; On the Nature of the Positive Rays, their Deflection by; Electric and Magnetic Forces 16; Electrostatic Deflection of the Particle 19; Wien's Proof of the Magnetic and Electric Deflection of; the Rays 22; Experiments made by the Author on Positive Rays 25; Effect at very Low Pressures 27; Method of Hot Cathodes 35; Aston's Focus Method 36; Dempster's Method 40; Discussion of the Photographs 41; Loss and Gain of Charge by Particles 48; Ionization by Positive Rays 54; Secondaries 60; Negatively Charged Particles 70; Multiply Charged Particles 77; Concentration of the Positive Rays round Definite Velocitdxs 84; Origin of the Charged Atoms and Molecules in the Positive; Rays 88; Electric Force in the Dark Space 108; Method of Consecutive Systems of Electric and Magnetic; Flelds -117; --This text refers to an alternate Paperback edition.