The nature of the intermolecular force field of the nitriles is considered on the basis of the electron orbital structure and charge distribution of the nitrile group. The directional nature of the force field is due to a well-directed lone pair orbital on the N atom, which may be expected to exhibit strong donor properties, and two π-orbitals which may exhibit weak donor properties. Accordingly with good acceptor molecules such as chloroform and hydrogen chloride, simple 1:1 molecular addition compounds should occur. The existence of molecular complexes of this type was confirmed with the aid of binary freezing-point diagrams which were determined for aceto-, propio-, butyro-, and benzo-nitrile with chloroform and hydrogen chloride. The 1:1 association complex was absent, however, in the system acetonitrile–chloroform. This is accounted for by the stronger association occurring in acetonitrile itself, the nature of which is discussed. The structure of the 1:1 molecular complexes is considered. Additional molecular complexes with lower nitrile mole ratios are indicated in the freezing-point diagrams. Of particular interest are the well-defined compounds appearing in the nitrile – hydrogen chloride systems with the composition RCN•5HCl. The possibility that the π-orbitals of the nitrile group may function as donors in these compounds is discussed, and a tentative structure is suggested.

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A method of measuring density gradients caused by gravitational compression in gases near the critical region is described. Relative light scattering coefficients of ethane in bombs 40 cm. long increase, remain constant, or decrease in the downward direction, depending upon the mean filling density. These observations have been correlated with the variation of scattering coefficient with density, and show that appreciable density gradier~ts exist. These observations are confirmed by parallel studies of condensation, and serve to explain the flat portion of the liquid-vapor coexistence curve found with a carefully puritied system. INTRODUCTIONThe variation of pressure with height in an isothernlal fluid is given by the equation where x is the vertical distance (downwards) from a datum. and p and v respectively are the density and specific volume. Using the transformation and introducing the isothermal compressibility = ---, one can write t ( Z ; ) . Equation ( I ) in the form :Near the liquid-vapor critical point, a t which P -+ m , Equation ( and p , = 0.73 gm. per cc., the density gradient calculated from Equation (2) is 0.9 % per cm. For a methane-propane mixture of unstated AT, Blosser and Drickamer (3) report fl = 112 atn1os.-I a t p = 0.21 gin. per cc., a value derived from light scattering measurements. The calculated gradient for this case is 2.4% per cm.

Turbidity measurements in the region immediately above the critical temperature are used t o calculate values of ( a p l a u )~. These results show that ( a p l a v )~ is a continuously variable function of the density t o within 0.02"C. above the critical temperature. The experiments indicate that there esists no region above T, throughout which (ap/av)T = 0 in ethylene or xenon.

The catalyst activities for Na2S oxidation in aqueous solution were examined for various materials such as activated carbon, carbon black, ferric salts, hydroquinone, 1,4-naphthoquinone-2-sulfonic acid sodium salt, 1,4-naphthoquinone, and their mixed systems.The following conclusions have been drawn: (1) These catalyst systems are all active. (2) The effect of carbon black-ferric sulfate-system or hydroquinone-ferric chloride-system on oxidation efficiency is larger than that of carbon black or hydroquinone alone. (3) In case of carbon black system, the experimentally determined requirement of air is, respectively, about 40, 15, and 10 times larger than theoretical, corresponding to the runs of no catalyst, carbon black, and carbon black-ferric sulfate-system. In case of hydroquinone system, air requirements are, respectively, about 40, 15 and 8 times, corresponding to the runs of no catalyst, hydroquinone-ferric chloride-system and hydroquinone-ferric chloride-ammonium peroxydisulfate-system. (4) Application of the catalyst systems studied was made to wastewater and sludge treatments. These catalyst systems gave good results.