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Grateful acknowledgment is made to the National Research Council of Canada and to the Imperial Oil Co. of Canada for financial support which made possible the purchase of the gas chromatograph.

Previous tabulations of enthalpies of formation of perchloric acid solutions are not in agreement with the behavior espected for an acid as highly dissociated as perchloric acid. Measurements of the heats of neutralization of perchloric acid solutiolls with sodium hydroxide solutions were made and new values of the relative apparent partial molal enthalpies of perchloric acid solutions in the range 1 t o 24 molal were con~puted from these. These new values agree with the anticipated behavior of perchloric acid.Traditionally, any deviations of strong electrolyte solutions from ideal behavior are explained in terms of interionic attraction, dissociation of structures, and solvation of the ions produced in dissociation. Considering their effects on the heat of d i l u t i o~~, the first two will tend to make the process endothermic, while the third is an exothermic process. Lacking both theoretical and experimental information about the interionic attraction effects in concentrated electrolyte solutio~ls, one can adopt as a working hypothesis the fact that, as a first approximation, for a given electrolyte type, heat of dilution contributions from these effects will be a function only of ionic strength but not of the specific nature of the electrolyte. Specific differences in heats of dilution of strong electrolyte solutioils will then be explainable as differences in hydration and degree of dissociation. This view is confirmed by the similarity of the relative enthalpies of solutio~ls of salts of the larger alltali metal iolls with large anions (7), where we anticipate little hydration and complete dissociation.Such a simplified picture is consistent with the tabulated values of the heats of formation of nitric acid solutions ( 5 ) . Nitric acid is known to be incompletely dissociated even a t relatively low concentration (8, 9), so that on dilutioil a n appreciable number of protons are dissociated and upon hydration liberate sufficient energy that the over-all heat of dilution of nitric acid is exothermic a t all concentrations appreciably removed from infinite dilution.Perchloric acid is a much stronger acid than nitric acid. Undissociated perchloric acid can be detected a t high concentrations, but below the vicinity of eight molal the concentration of undissociated molecules is too low to be detected (10). At very high concentrations it is to be expected that perchloric acid will resemble nitric acid in showing a substantially exothermic heat of dilution to infinite dilution, but in the vicinity of eight molal, as protons cease to be made available in quantity for the exothermic solvation process, there For personal use only.

A consideration of factors known to govern the formation of coordination compounds with metal ions led to the conclusion that the best ligands to use in attempting to separate beryllium from other metal ions of inert gas configuration by liquid–liquid extraction would be easily polarizable, monofunctional ligands. It is suggested that the thiocyanate ion, as ammonium thiocyanate, is particularly promising for metallurgical application.The organic solvent was shown to play an active role in the extraction, ketone or hydroxy groups on chains containing six to eight carbons giving good extraction with low solvent loss.