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The kinetics of the oxidation of uranium (IV) by thallium (III) in the presence of tartaric acid was investigated in aqueous perchloric acid solutions. Increases in initial rate with increasing tartaric acid concentrations were observed, along with departure from the second-order rate law. The orders with respect to uranium (IV), thallium (III), tartaric acid, and hydrogen ion were found to be 0·93, 0·05, 0·37 and −0·91, respectively. Thallium (III) in the presence of tartaric acid was shown to be stable by polarography, yet in kinetics experiments with Tl(III) in excess over uranium (IV), the reaction stopped because the Tl(III) was consumed. The oxidation of U(IV) by oxygen of the air is catalysed by the presence of tartaric acid, but this reaction is negligibly slow compared to the U(IV)Tl(III)-tartaric acid reactions. The presence of U(VI), and Tl(I) were shown to have no effect on the reaction kinetics. A mechanistic interpretation has been developed to account for the observed results.

Various factors affecting the electrical resistivity of the pyrotechnic pressed powder TiH/sub x//KC10/sub 4/, which is sensitive to hot wire ignition yet quite spark insensitive, were evaluated. The electrical resistivity of the TiH/sub x/ and TiH/sub x//KC10/sub 4/ were correlated with their pressing pressure, stoichiometry, powder surface area, and temperature (from below liquid nitrogen temperature to 500 K). Data show resistivity increasing with x and surface area, and decreasing non-linearly with pressing pressure. It was concluded that temperature coefficient of resistivity depends upon powder surface features. In addition, it was found that electrostatic discharge lowers TiH/sub x/ and TiH/sub x//KC10/sub 4/ pellet resistivity and that the effect is larger for pellets with higher initial resistivity.