than LLO over the entire temperature range; however, at the higher temperatures the viscosities of D»0 and H20 appear to approach each other. For example, at 5°the difference between the viscosity of D20 and H20 is 0.4628 cP while at 70°the difference is only 0.0693 cP. One might attribute the decrease in the difference between the of D20 and H20 to the formation of similar structure for D20 and H20 at high temperatures (i.e., if the larger of D20 is due to greater structure). The effect of temperature on the differences between the compressibilities of' DO and H>0 also agree with this suggestion (3,4,12).

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Techniques of zone melting were applied to systems of organic compounds using a simple apparatus which allowed the passage of 18 molten zones through the sample during a single run.Spectrophotometric analysis indicated that the methyl violet concentration in naphthalene could be lowered to 1 p.p.m. by a single passage through the 18-zone column. Similarly, combustion of samples followed by counting of the CO2 in an ionization chamber showed that the concentration of carbon-14labeled naphthalene in benzoic acid could be lowered to less than one part per 10 million using this zone refiner.

Polarization curves of the hydrogen evolution reaction are presented for rhenium and niobium electrodes in dilute hydrochloric acid solutions as a function of temperature. The Tafet reaction is the rate-determining step in the hydrogen evolution reaction on rhenium. The behavior of niobium electrodes is much more complicated. The presence of the passive oxide layer on niobium produces an ohmic contribution to the total overvoltage. The corrected activation-overvoltage curves for niobium show a change of Tafel slope which is consistent with a Volmer-Tafel mechanism if certain assumptions are made about the distribution of potential at the interface. Activation energies of the hydrogen reaction are computed for both rhenium and niobium electrodes.Comparatively few studies on the electrochemical behavior of rhenium and niobium electrodes have been reported. Pecherskaya and Stender (1) measured hydrogen overvoltage on rhenium. Hydrogen overvoltage on niobium was studied by Bockris (2), by Kononchuk and Barmashenko (3), and by Rotinyan and 1Present address: ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 139.80.123.38 Downloaded on 2015-03-15 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 139.80.123.38 Downloaded on 2015-03-15 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 139.80.123.38 Downloaded on 2015-03-15 to IP