The influence of nitrogen peroxide on the combination of hydrogen and oxygen

It has recently been shown that small traces of nitrogen peroxide exert a remarkable influence on the combination of hydrogen and oxygen, even at temperatures far below that at which the normal reaction has an appreciable velocity. At any such temperature there exist two sharply defined critical concentrations of nitrogen peroxide, between which there is instantaneous inflammation of the hydrogen and oxygen, but above or below which there is only an extremely slow reaction. The transition at each of these nitrogen peroxide pressures is very abrupt. An analogues phenomenon can be observed in the union of oxygen and hydrogen alone. Between certain limiting concentrations there is immediate explosion, but above and below these a reaction with a measurable velocity takes place.