XX CONTENTS. 



CATHODE AND CANAL RAYS 



489. Cathode and canal rays 386 



490. Speed of cathode rays 386 



491. Cathodic sputtering 386 



R6NTGEN (X-RAYS) RAYS 



492. X-rays, general properties 387 



493. Rontgen secondary rays 387 



494. Corpuscular rays 388 



495. Intensity of X-rays; ionization 388 



496. Mass absorption coefficients, \/d 389 



497. Absorption coefficients of characteristic radiations in gases 389 



498. X-ray spectra and atomic numbers 390 



(a) K-series 390 



(b) L-series 391 



(c) M-series 392 



(d) Tungsten X-ray spectrum 392 



499. X-ray absorption spectra and atomic numbers 393 



RADIOACTIVITY 



500. Relative phosphorescence excited by radium . 394 



501. The production of a particles (Helium) 394 



502. "Heating effect of radium and its emanation 394 



503. Stopping powers of various substances for a rays 395 



504. Absorption of ft rays by various substances 395 



505. " 7 rays by various substances 395 



506. Table of miscellaneous properties 396 



507. Total number of ions produced by the a, /3, and 7 rays 398 



508. Amount of radium emanation 398 



509. Vapor pressure of the radium emanation in cm of Hg 398 



510. References to spectra of radioactive substances 398 



MOLECULAR, ATOMIC AND IONIC DATA 



511. Molecular velocities 399 



512. free paths, collision frequencies and diameters 399 



513. Cross sections and lengths of some organic molecules 400 



514. Size of diffracting units in crystals 400 



515. Electrons; Rutherford atom; Bohr atom; Magnetic field of atom . . 401 



516. Electron emission from hot metals 403 



517. Photo-electric effect 403 



518. Ionizing potentials, resonance potentials, single line spectra .... 403 



519. Contact (Volta) potentials 404 



(a) Electron affinity of the elements 404 



(b) Voltage of electrolytic cells 404 



520. Ionic mobilities and diffusions, ionic mobilities 405 



521. Diffusion coefficients 45 



