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The kinetics of the thermal decomposition of ethyl nitrate in the gas phase have been studied in the temperature range 175"-209" C. The initial rate of pressure rise has been used to deduce the first-order rate equation k = 1014-74 exp ( -38,000 f 380)/RTsec-1.Additional information has been obtained from photometric measurements of the nitrogen dioxide concentration throughout the reaction. Ethyl nitrite has been detected in the products of the ethyl nitrate + nitric oxide reaction at 190" C by u.-v. spectrophotometry, and ethyl nitrate has been detected in the products of the ethyl nitrite + nitrogen dioxide reaction at 190" C by gas chromatography. By standard analytical techniques it has been shown that the final gaseous products are CO2, CO, NO, N20 and N2, with possibly a trace of hydrogen.The effects of added nitric oxide and nitrogen dioxide are discussed in terms of the probable reactions in the normal case.

The non-explosive reaction between nitrogen dioxide and formaldehyde has been studied over a range of temperatures between 1 1 8 O C and 184" C. It has been shown that up t o 160' C the reaction is homogeneous and the rate proportional t o pHCHO , pNOI. The value of k is given by k = 1c7.le -159100/RT l./mole sec. The products of the reaction are mainly NO, CO, C 0 2 and H,O, with possibly some N, and N,O, but no hydrogen was observed among the gases. The ratio CO/CO, was practically constant throughout the course of the reaction. A possible mechanism is suggested t o account for the experimental results, and attention is drawn t o the low values of the B factor for other reactions involving Above 1 6 0 O C there appears t o be some change in mechanism, for which k is estimated to be 10@e -19*000/RT, and a t still higher temperatures the reaction becomes explosive. NO 2.I n studies of gas-phase oxidative reactions, nitrogen dioxide, as the main oxidizing agent, has received very little attention, though of course it is well known that the addition of small quantities of nitrogen dioxide has a marked effect on the kinetics of the oxidation of hydrogen, carbon dioxide, etc., by oxygen. Only two reactions involving oxidation by nitrogen dioxide have been reported in any detail, namely the oxidation of carbon monoxide 1 and sulphur dioxide 2 respectively.The oxidation of organic molecules by nitrogen dioxide is of particular interest in elucidating the mechanisms involved in the thermal decomposition of nitric esters.that the primary process in such decompositions is the breaking of the O-NO2 bond. The remaining alkoxy fragments give rise to alcohols and aldehyde^.^ These alcohols and aldehydes react with the nitrogen dioxide formed in the primary process to give oxides of carbon, and lower oxides of nitrogen.These papers deal with the slow and explosive oxidation of the simplest aldehyde, viz. formaldehyde by NO,. It has been suggested 3, 4 3 5, Experiment a1 Materia~s.-~ORMALDEHYDE.-~on0meric formaldehyde was prepared by NITROGEN DIOxIDE.-Liquid nitrogen tetroxide supplied by the I.C.I. Ltd.the method of Spence and Wild,s and stored a t liquid air temperature. was sublimed in vacuo, and stored a t -80" C.