TRENDS
Sublimation i s a unit operation that could receive much greater attention in the future as a purt$ication method. Clare A . Holden and Howard S. Bryant, Mobil Chemical Co., Edison, N . J . [Separation Science, 4 (I), 1-73, 19691 review this method of purification from a frequent batch process used for simple separation of a desired volatile constituent from a volatile impurity, to a continuous, multistage method for fractionating materials of dayering volatility on a large industrial scale. The method will be particularly important for materials that decompose at temperatures below the melting point and that have low solubilities in common solvents. More experimental information, particularly the factors influencing the condensation of solids from the vapor, would be of value in design of equipment. Laminae column foaming i s a special type of foam separation. The foam is degraded to fast-moving, nearly planar laminae, which are rinsed by reJlux. This method, described by Klaus Maas, Organic Chemical Institute of the University of Heidelberg, Heidelberg, Germany [Separation Science, 4 ( 1 ) ) 69-81, 19691, is distinguished by a simple technique-i.e., quick establishment of the steady state-and the possibilities of working with low-foaming solutions and handling small quantities of substances. The author describes the phenomena of the laminae column foaming, types of laminae producers, countercurrent columns, and laminae destroyers with a complete apparatus with circulating gas. Periodic hydrodynamic disturbances of the gas flow rate in packed adsorption columns can influence the column eficiency. Gas phase pulsations, due to the increased turbulence which they induce at the interface, can result in a considerable increase of mass transfer coejicients whose values may exceed 100yo in suitable operating conditions, according to A . Gianetto and S. Sicardi, Istituto di Chimica Industriale del Politecnico, Torino, Italy [Ingengere Chimico Italiano, 5 ( 4 ) )47-54, 1969]. A proposed mathematical model was ver$ed experimentally for various operating conditicns. An improved viscosity-temperature chart for hydrocarbons, used in a wide variety
of high-temperature fluids, has been prepared by W . A. Wright, research scientist at Sun Oil Co., Marcus Hook, Pa. [ J . Materials, 4 (I), 79-27, 19691. This chart has
greatly improved linearity and useful range as compared to the present ASTM Designation 0341 and others, thereby making it more widely useful. The mathematical expression was derived empirically from current data on both pure hydrocarbons and petroleum fractions. The improved chart will permit reliable linear extrapolations into low-viscosity, high-temperature regions which were not possible previously. Fundamental issues of statistical methods in scient@ inference have not been resolved, according to A. W. F. Edwards, Gonville and Caius College, Cambridge, England [Nature, 222, 1233-7, 19691. He presents a short account of the more influential points of view. Statistical hypothesis is defined, and the concept of prior likelihood is introduced as a means of completing a scheme of inference which does not share the logical disadvantages of other methods. According to Edwards, the essential statistical feature is that it is possible to attach a probability to each of the possible outcomes, and itspeculiarity is that it cannot be directly verified. 2
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
