contents. xxi 



Colloids 



General properties of colloids 406 



Molecular weights of colloids 406 



Brownian movement 406 



Adsorption of gas by finely divided particles 407 



Heats of adsorption 407 



Molecular heats of adsorption and liquefaction 407 



Miscellaneous constants, atomic, molecular, etc 408 



Radiation wave-length limits 408 



Periodic system of the elements (Mendelejeff) 409 



Atomic numbers 409 



Periodic system of the elements and radioactive isotopes (Hackh) . . 410 



Astronomical Data 



Stellar spectra and related characteristics 411 



The Harvard spectrum classification 411 



Apex and velocity of solar motion 411 



Motion of the stars 412 



Distances of the stars 412 



Brightness of the stars 413 



Masses and densities 413 



Miscellaneous astronomical data 414 



The first- magnitude stars 415 



Wolf's observed sun-spot numbers, 1750 to 19 17 415 



Length of degrees on the earth's surface 416 



Equation of time 416 



Planetary data 416 



Numbers and equivalent light of the stars 417 



Albedos 417 



Duration of sunshine 417 



The solar constant 418 



Solar spectrum energy and its transmission through the atmosphere . 418 



Intensity of solar energy in various sections of spectrum 418 



Distribution of brightness (radiation) over the solar disk 418 



Transmission of radiation through moist and dry air (see Table 376) . 419 



Brightness of sky at altitudes of 1730 m and sea-level 419 



Relative distribution in normal spectrum of sun and sky light ... 419 



Air masses 419 



Relative intensity of solar radiation for various months 420 



Meteorological Data 



558. Mean monthly and yearly temperatures for representative stations . 420 



559. The earth's atmosphere, variation with latitude, miscellaneous ... 421 



