Page:Radio-activity.djvu/587

 analysis of α ray curves, 377 α ray curves of, 378 β ray curves of, 379 analysis of β ray curves, 381 equations of activity curves, 389 effect of temperature on, 390 volatility of, 391 of slow transformation, 311, 397 variation of α ray activity of, 398 variation of β ray activity of, 399 separation of constituents of, 401 et seq.    successive products in, 402     variation of activity of, for long periods, 407     presence in old radium, 408     effect of, on variation of activity of radium with time, 409     presence in pitchblende, 410     connection with radio-tellurium, 411     connection with polonium, 411, 412     connection with radio-lead, 413     connection of, with radio-active induction, 415 et seq.     heat emission of, 425 et seq.     use of, to determine number of β particles from radium, 435     use of, as source of α rays, 543  Des Coudres   magnetic and electric deviation of α rays, 148   determination of e/m for α rays, 148  Dewar   emission of heat from radium in liquid hydrogen, 420  Dewar and Crookes   absence of nitrogen spectrum in phosphorescent light of radium at low pressures, 206  Dewar and Curie   production of helium by radium, 479  Dielectrics   condition of, under radium rays, 209  Diffusion   of ions, 51 et seq   of radium emanation into gases, 270   of thorium emanation into gases, 275   of radium emanation into liquids, 276  Discharge   action of rays on spark and electrodeless, 208  Disintegration   account of theory of, 234, 325, 445   list of products of, 449   rate of, in radio-elements, 457   emission of energy in consequence of, 474 et seq.   helium a product of, 476 et seq.   possible causes of, 486 et seq.   of matter in general, 496 et seq.

Dissipation of charge in caves and cellars, 514 et seq.  in closed vessels, 531   effect of pressure and nature of gas on, 534 et seq.   effect of material of vessel on, 536 et seq.

Dolezalek electrometer, construction of, 94 et seq.

Dorn charge carried by β rays, 122 electrostatic deflection of β rays from radium, 124 discovery of radium emanation, 246 effect of moisture on emanating power of thorium, 255 electrolysis of radium solution, 313 loss of weight of radium, 474 radium emanation in springs, 513

Dreyer and Salomonsen coloration of quartz by radium rays, 213

Dunston analysis of thorianite, 486

Durack ionization by collision of electrons of great velocity, 171

Dust effect of, on recombination of ions, 42 effect of, on distribution of excited activity, 305

Earth amount of radium in, 493 et seq. age of, 496 excited activity deposited on, 504 activity concentrated on peaks of, 504 emanation from, 507 very penetrating radiation from, 520

Ebert condensation of emanation from the earth, 510 apparatus for determining number of ions per c.c. in air, 527 velocity of ions in air, 528

Ebert and Ewers emanation from the earth, 508

Electrolysis separation of radio-tellurium by, 25 of solutions of active deposit, 313 of radium solutions, 313 of thorium solutions, 314

Electrometer description of, 90 et seq. use of, in measurements, 90 construction of, 91 et seq. Dolezalek, 94