Page:Radio-activity.djvu/593

 Makower diffusion of radium emanation, 274 diffusion of thorium emanation, 276

Marckwald preparation of radio-tellurium, 25 rate of decay of radio-tellurium, 411

Mass apparent mass of electron, 71, 127 variation of mass of electron with speed, 127 et seq.  of α particle, 147 et seq.

Materials radio-activity of ordinary, 528, 536 et seq.

Matteucci rate of dissipation of charge in closed vessels, 531

McClelland absorption of γ rays, 181 secondary rays from β and γ rays from radium, 192

McClung coefficient of recombination of ions, 41 conductivity of gases exposed to X rays, 64 ionization by α rays from radium C, 550

McClung and Rutherford energy required to produce an ion, 58 variation of current with thickness of layer of uranium, 195 estimate of energy radiated from radio-elements, 418 radiation of energy from radium, 438

McLennan absorption of cathode rays, 65 radio-activity of snow, 506 excited radio-activity at Niagara Falls, 519

McLennan and Burton penetrating radiation from the earth, 520 radio-activity of ordinary materials, 537 emanation from ordinary matter, 538

Metabolon definition of, 446 table of metabolons, 449 radio-elements as metabolons, 457

Meteorological conditions effect of, on radio-activity of atmosphere, 517

Methods of measurement in radio-activity, 82 et seq.  comparison of photographic and electrical, 83 et seq.   description of electrical, 84 et seq.

Meyer and Himstedt production of helium by radium, 479

Meyer and Schweidler magnetic deviation of β rays by electrical method, 113 absorption of β rays of radium by matter, 136 activity proportional to amount of uranium, 195 emanation from uranium, 348 effect of crystallization on activity of uranium, 349 rate of decay of radio-tellurium, 411

Minerals, radio-active constant ratio of radium to uranium, 459 et seq.  list of minerals, 461   age of, 485   composition of, 554 et seq.

Mobility of ions, 43 et seq.

Moisture effect of, on velocity of ions, 43, 45 effect of, on emanating power, 255

Molecule number of, in 1 c.c. of hydrogen, 54

Molecular weight of radium emanation, 273 of thorium emanation, 275

Nagel and Himstedt action of radium rays on the eye, 217

Niewenglowski rays from sulphide of calcium, 4

Nomenclature of successive products, 328 et seq.

Number of molecules per c.c. of hydrogen, 54 of ions produced in gas by active substances, 55 of β particles expelled from 1 gram of radium, 124 of α particles emitted per gram of radium, 155 of ions produced per c.c. in closed vessels, 534

Occlusion of emanation in thorium and radium, 258 of radium emanation by solids, 310

Owens saturation current affected by dust, 42 penetrating power of rays independent of compound, 164 absorption of α rays varies directly as the pressure of gas, 169 effect of air currents on conductivity produced by thorium, 238

Oxygen change into ozone, by radium rays, 213