cc.)(cm.)/(sec.)(sq. cm.)(cm. Hg) a t any temperature covered, while the smallest value for the porous Vycor glass is 10-5 in the same units. Besides, the porosity of the porous Vycor glass is 0.3 ; therefore, bulk flow thorugh nonporous glass must be negligible. Leiby and Chen (1960) also studied the permeation of helium through Vycor glass ; their findings verified Norton’s data. We are not in any way concerned with Satterfield and Cadle’s interpretation of their own data. The adequacy of such interpretation must be judged by the readers. We, howrever, feel that Satterfield and Cadle’s comments concerning our surface flow findings are incorrect and that their arguments are untenable. Nomenclature
C, = concentration of adsorbed phase D, = surface diffusivity, sq. cm./sec. F , = surface flow rate, std. cc./sec. G2 = geometric factor k, = Henry’s law constant M = molecular weight, g./g. mole. P = pressure, cm. H g
Q = permeability, (std. cc.)(cm.)/(sec.) (sq. cm.)(cm. Hg)
S
= cross-sectional area, sq. cm.
T = temperature,
OK.
literature Cited
Hwang, S.-T., Ph.D. thesis, University of Iowa, 1965. Hwang, S.-T., Kammermeyer, K., Can. J . Chem. Eng. 44, 8 2 (1966a). Hwang, S.-T., Kammermeyer, K., Separation Sci. 1 (5), 629 (1966b). Hwang, S.-T., Kammermeyer, K., Separation Sci. 2 (4), 555 (1967). Hwang, S.-T., A.Z.Ch.E. J., inpress, 1968. Leiby, C. C., Jr., Chen, C. L., J . Appl. Phys. 31,268 (1960). Norton, F. J., J . Am. Ceram. Sod. 36,90 (1953). Perry, E. S., “Progress in Separation and Purification,” Vol. 1, p. 335, Wiley, New York, 1968. Satterfield. C. N.. Cadle, P. J., IND.ENG.CHEM.FUNDAMENTALS 7, 202 (i968). . Steele, W. A., Halsey, G. D., Jr., J . Phys. Chem. 59, 57 (1955). Tack, R. W., Kammermeyer, K., A.I.Ch.E. J., in press, 1968. Sun-Tak Hwang Karl Kammermeyer
University of Iowa Iowa City,Iowa
Correction
GENERAL BALANCE EQUATION PHASE INTERFACE
FOR A
I n this article by John C. Slattery [IND.ENG.CHEM.FUNDA6, 108 (1967)], e should be replaced by e in Equations 5.21, 5.22, 5.232, 5.24, 6.2, 6.3, 6.4, 7.2. 7.3, 7.4, and 7.6. I n the Nomenclature, it is ea,&which is defined by Equation 5.22.
MENTALS
672
l&EC FUNDAMENTALS
