The decomposition of hydrogen peroxide (at partial pressures of one to two millimeters of mercury) was studied in the presence of one atmosphere of oxygen or nitrogen by the use of a flow system. The concentration of H2O2 was measured photometrically, using the continuous ultraviolet absorption of this compound. Determination by this means was more rapid, and offered less chance for errors of manipulation than conventional chemical analysis. A first order reaction with an activation energy of 40 kcal./mole was found in the neighborhood of 520°C. Evidence is presented to support the conclusion that the reaction is partly, at least, homogeneous in boric acid treated vessels at temperatures in the 470 to 540°C range.

The absorption coefficient for hydrogen peroxide vapor in the wave-length range 1850–2200A was determined. A careful redetermination of the absorption coefficients for the vapor and for aqueous solutions at 2537A was also made.

Three methods were used to obtain electron density as a function of radius in a magnetically confined, low-pressure argon arc. The first utilized the phase shift of a reflected 35-kMc/sec microwave, and the second determined density from the ion saturation current to a Langmuir probe. The third determination utilized the broadening of the H β line emitted by a small quantity of added hydrogen. Agreement among the three methods is satisfactory; the electron density at the axis of this discharge is of order 1014 cm−3, in agreement with results obtained by others for discharges of similar type.

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