It has long been suspected that if liquids were sheared sufficiently rapidly they would exhibit a shear elastic effect as well as a viscous effect. This supposition was verified recently by one of the writers (see reference 8) by employing a torsionally vibrating crystal and measuring the mechanical loading for the shear wave by observing the increased resistance at resonance and the change in the resonant frequency. By this method it was shown that long chain polymer liquids had shear configurational elasticities in the order of 10 7 dynes/cm 2 .The use of a torsional crystal is limited in frequency to about 2 to 3 X10 5 cycles on account of the small sizes needed. In the present paper the range of shear wave measurements in liquids has been extended up to 60 megacycles by observing the effect, on a series of shear waves in a fused quartz rod, of terminating the rod by a thin layer of a liquid. The shear wave in the rod is altered in magnitude and phase by the boundary layer impedance of the liquid. By observing the reflection loss and the change in phase caused by the liquid layer, a measure is obtained of the shear impedance of the liquid. By employing a fused quartz rod for which the shear wave strikes the reflecting surface at an angle from the normal of about 79 degrees, the effect of the shear wave impedance on the boundary is greatly enhanced and a more accurate measurement obtained.Both the torsional crystal and high frequency shear wave techniques applied to polyisobutylene and poly-a-methylstyrene liquids, show that there are two main relaxation frequencies in these liquids. At frequencies under 100 kc, the shear stiffness is in the order of 3X10 7 dynes/cm 2 , while in the high megacycle range it has increased to 5 X10 9 dynes/cm 2 . The low shear elasticity appears to be associated with a composite motion of molecular rotation and translation that allows a configurational change to occur from the most probable chain shape. When the shear stress is removed, the molecule quickly returns to its most probable shape. This results in a low shear stiffness. At high frequencies this motion cannot take place, and the shear stiffness is determined by motions within single potential wells, and the value approaches that for a crystal. It is shown that the dispersion for longitudinal waves measured recently (see reference 11) is primarily due to the shear mechanisms investigated. L INTRODUCTIONI T HAS long been suspected that if liquids were sheared sufficiently rapidly, they would exhibit a shear elastic effect as well as a viscous effect. In fact, Maxwell, 1 on the basis of a gas model, predicted that an instantaneous shear distortion would have a relaxation time r and a relaxation frequency jv given by the formulas T = r}/n\ / r ==l/(27rr)=M/(27n?),(1) where t\ is the shear viscosity and \x the shear elasticity. A similar result has recently been obtained by Frenkel 2 by assuming that a liquid has a short range order similar to a solid, and identifying the relaxation time r as the mean life in a sedentary stat...

The reliability of the reactions used to locate (10) After completion of this investigation, Dr. Ruben informed us by private communication that they have been unable to duplicate their previous results1 2345 and have now found radioactive carbon only in the carboxyl group of the propionic acid. carbon dioxide fixed in propionic acid by bacterial fermentations has been investigated.Alkaline permanganate oxidation is not a reliable method of decarboxylating propionic acid.Dry distillation of barium propionate gives reliable results under proper experimental conditions. The results have been obtained using synthetic propionic acid containing the isotope of carbon (C13) as a tracer of carboxyl carbon.

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The containers used for steel slag transportation to the recycling depot undergo hightemperature gradients and often deform plastically. Also, parts of the thereby solidified slag adhere to the pot walls, causing demolding problems and wear. A thorough finiteelement analysis of the heat transfer, initiated by filling the pots and essentially driven by radiation, and the thermal stresses is performed. Due to periodic fill-in and discharge, these are assumed to admit a quasi-stationary state referring to the pot temperature before their emptying. The so obtained results aid optimizing the pot shape and the transport process in terms of minimizing maintenance and anti-adhesive cladding. A layer of solidified slag is found to exist throughout the transport process. Although the phase change occurs almost instantaneously at a liquid-solid interface, the "mushy zone" is considered in the accompanying analytical study of the associated Stefan-type problem. Good correlations of the predicted temperatures to the measured ones and the resultant surface damaging are obtained.

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