The rapid growth of interest in powders and their surface properties in
many diverse industries prompted the writing of this book for those who
have the need to make meaningful measurements without the benefit of
years of experience. It is intended as an introduction to some of the
elementary theory and experimental methods used to study the surface
area, porosity, density, and particle size of powders. It may be found
useful by those with little or no training in solid surfaces who have
the need to learn quickly the rudiments of surface area, density, pore
size, and particle size measurements. S. Lowell J.E. Shields Symbols Use
of symbols for purposes other than those indicated in the following
table are so defined in the text. Some symbols not shown in the table
are also defined in the text. d adsorbate cross-sectional area A area;
condensation coefficient; collision frequency C BET constant c
concentration D diameter; coefficient of thermal diffusion E adsorption
potential permeability aspect factor f F flow rate; force; feed rate g
gravitational constant G Gibbs free energy S G free surface energy h
heat of immersion per unit area; height H enthalpy heat of immersion Hi
heat of adsorption Hsv BET intercept; filament current k thermal
conductivity; specific reaction rate K Harkins-Jura constant C length L
heat of liquefaction M mass M molecular weight MPa megapascals number of
moles n number of molecules; number of particles N N Avogadro's num'ber
molecular collisions per square cm per second
