408 



TABLES 528-529. 

 TABLE 528. Miscellaneous Constants (Atomic, Molecular, etc.). 



Elementary electrical charge, charge on electron, i charge on a particle t = 4-774 * I0 ~ 10 esu ( M ) 



= 1.591 X io- 2 emu 



= i . 591 X io- coulomb 



Mass of .an electron i* = 9 . 01 X io~ 28 g 



Radius of an electron about 2 X io^ 13 cm 



Ratio elm, small velocities e/m = i. 766 X io 7 emu. g -1 



Number of molecules per gram molecule or per gram molecular weight (Avogadro 



constant) N = 6.062 X io (M) 



Number of gas molecules per cm 3 , 76 cm, o C (Loschmidt's number) n = 2.705 X io 19 (M) 



Number of gas molecules per cm j , o C at i X io 6 bars 2 . 670 X io lj 



Kinetic energy of translation of a molecule at o C Eo 5 . 621 X io~ 14 erg (M) 



Constant of molecular energy, Eo/T - change of translational energy per C. . . e = 2.058 X io~ 16 erg/ 6 C (M! 



Mass of hydrogen atom : = i . 662 X to" 24 g (M) 



Radius of hydrogen molecule about : . io~ 8 cm 



Mean free path, ditto, 76 cm, o C, about Z, = i . 6 X io~ 6 cm/sec. 



Sq. rt. mean sq. velocity, ditto. 76 cm. o C G = 1.84 X 10* cm/ sec. 



Arithmetical average velocity, ditto. 76 cm. o C 12 = i . 70 X io 5 cm/sec. 



Average distance apart of molecules. 76 cm, o C = 3 X io~ 6 cm 



Boltzmann gas constant = constant of entropy equation = R/N = poVo/TN = 



(}) k = i .372 X io-" erg/ C 



Volume per mol(e) or gram-molecular weight of ideal gas, 76 cm, o C (i .01323 X 



io 6 bars) =22.412 liters 



Ditto, i X io bars, o C (75 cm Hg) = 22 . 708 liters 



Gas constant: PVm = RT. V m = vol. molec. wt. in g when P in g/cm 2 , V m in cm 3 R = 84. 780 g-cm/ C 



when P in atmospheres, Vm in liters R = o. 08204 /-atm/ C 



when P in dynes, Vm in cm 3 R =8.315 X io 7 ergs/ C 



Absolute zero = o Kelvin = 273.13 C 



i Mega bar (= Meteorological "bar") = io dynes/cm 2 = 1.013 kg/cm 2 =0.987 atmosphere 



Mechanical equivalent of heat, i g (20 C) cal = 4. 184 X io 7 ergs 



= 4. 184 Joules 



Faraday constant F = 96494 coulombs 



Velocity of light in vacuo c = 2. 99860 X io 10 cm/sec. 



Planck's element of action h = 6. 547 X xo"" 27 erg. sec. (M) 



Rydberg's fundamental frequency Vo = 3 . 28880 X io 15 sec." 1 



Rydberg's constant. Vo/c N = 109678 . 7 



\Vien's constant of spectral radiation ct = i. 4312 for X in cm (M) 



Stefan-Boltzmann constant of total radiation <r = 5 . 72 X io~ 12 watt/cm 2 (M) 



Grating space in calcite d = 3 . 030 A 



Grating space in rock-salt (Uhler, Cooksey) = 2 . 814 X io~ 8 cm 



Potential difference in volts for X-rays of wave-length X in cm = FX = hc/e = i. 241 X io~ 4 volt, cm 



Reference: (M) Millikan, Phil. Mag. 34, i, 1917. 



TABLE 529. Radiation Wave-length Limits. 



Hertzen waves, longest 2 coo ooo. o cm 



shortest 0.2 cm 



Infra-red, longest, reststrahlung, focal-isolation 0.03 cm 



Infra-red, spectroscopically studied 0.002 cm 



Visible, longest 



shortest 



Ultra-violet, Lyman, shortest * 



X-rays, longest 



shortest 



7 rays, longest 



shortest 



o . ooo 08 cm 

 o . ooo 04 cm 

 o . ooo 006 cm 

 o . ooo ooo 1 2 cm 

 o.ooo ooo ooi cm 

 o.ooo ooo 013 cm 

 o.ooo ooo ooo 7 cm 



SMITHSONIAN TABLES. 



*o.ooooo2o cm (Millikan-Sawyer, 1920) 



