816 



SMITHSONIAN PHYSICAL TABLES 



Physical properties of materials — continued 



steel, 228 



strength, ultimate, 188 



tungsten, 225 



wood, 246 



zinc, 225 

 Pi (values), 6, 25 

 Piezoelectricity, 432 



crystals, 432 



strain coefficient, 432 



unit, 432 

 Pile yield of isotopes, 670 

 Planck's constant, 49, 51, 54, 79, 80 

 Planck's law, 7, 79 

 Planetary precession, 731 

 Planets (see also under Astronomy), 734 



orbits, 734 



physical data, 734 



satellites, 735 



temperature, 734 

 Plastics, characteristics, 239 



dielectric constant, 239 



dielectric strength, 239 



elasticity, 239 



index refraction, 240 



optical, 240 

 properties, 240 



specific gravity, 239 



thermal conductivity, 239 



thermal expansion, 239 

 Platinum, color temperature, 103 



cooling by radiation, 116 



emissivity, 98 



freezing point, 72 



thermocouples, 75 

 Pluto, 734 

 Poise, 318 

 Poisson's ratio, 227 

 Polarized light, rotation of plane, 557 



various materials, 557 

 Pole, Milky Way, 731 



North, 470 



South, 471 

 Positron, 651 



Potassium bromide, 515, 516 

 Potassium chloride, index refraction, 515 

 Potassium iodide, 515, 516 

 Potential difference, contact, 376 



alloys, 379 



aluminum vs. platinum, 376 



electrode, 637 



metals, 376, 378, 380 

 in solution of salts, 378 



solids vs. liquids, 376 



voltaic cells, 377 

 Potential excitation, 745 

 Pound (see under name of) 

 Pound weight, 6 

 Poundal, 6 

 Power, 6, 17, 22 



factor, 433 



insulating materials, 433 

 radio frequency, 433 

 Precession, 738 

 Pressure, boiling point, 119 



columns of mercury and water, 606 



conversion factors, 267 



Pressure — continued 



freezing point of water, 119 

 gases, critical, 276 

 melting point, 119 

 units of, 4, 638 



Van der Waal's equation, 262 

 volume relation (see also Compressi- 

 bility) : argon, 118 

 compounds, 286 

 gases, 261 

 metals, 286 

 nitrogen, 119 

 solids, 286-289 

 Probable error, 37 

 Propagation temperature, dust, 634 

 Proportional limit, 188 

 Proteins (see also Colloids), 631 

 Proton, 50, 654, 664 

 mass, 50 

 molecules, 631 

 pH stability, 634 

 synchrotron, 657 

 Pyrometer, optical (see also Optical pyrom- 

 eter), 97 

 glass, 537 

 Pyron, 9 



Quantity of electricity, 10, 11, 20 

 Quantity of light, 94 

 Quantum, 21, 89, 654 

 Quartz, crystal, 517, 518 



compressibility, 287 



dielectric constant, 428, 430 



fibers, characteristics, 534 



fused, 518 



index of refraction, 518 



physical properties, 534 



relative, volume with pressure, 289 



resistivity, 396 



rotation of plane of polarized light, 558 



transparency, 517, 546 



Radian, 6 

 Radiancy, 79 

 Radiant energy, 79 



absorption (see also Absorption), 517, 



535, 546 

 blackbody, 79 

 constants, 50, 80 

 first (ci), 50, 54, 80 

 density, 50 



second (cs), 50, 54, 80 

 different values, 80 

 definitions, 79 



Stefan-Boltzmann constant, 50, 52, 80 

 Wien displacement constant, 54, 80 

 cooling by, 112 

 definitions, 79 

 density, 50 

 flux, 79, 93, 94 



density, 79 

 intensity of source, 79 

 mechanical effects, 671 

 nickel, 101 



reflection, formula, 549 

 light, 549 



