MM. HAUTEFEUILLE AND CHAPPUIS, in continuing their investigation of the conditions under which oxygen is transformed into ozone, have shown in Compt. rend. that the character of the electric discharge to which the oxygen is subjected largely influences the quantity of ozone produced. If the discharge assume the character of a luminous shower the maximum amount of ozone is produced, the temperature of such a discharge being lower than that of the ordinary effluve. The production of this special form of discharge is ensured by mixing with the oxygen a small quantity of a foreign gas whose physical properties are dissimilar from those of oxygen; of the gases experimented with silicon fluoride has given the best results. If nitrogen be the foreign gas the transformation into ozone is greater than when pure oxygen is employed, but the discharge is not altogether luminous. Hydrogen is more effective than nitrogen. The presence of carbon dioxide also insures a large amount of ozonation. In their earlier experiments on the liquefaction of ozone the authors only succeeded in obtaining a mist in the Cailletet tube when the pressure was suddenly withdrawn. They now find that if a mixture of carbon dioxide and oxygen which has been ozonised at a low temperature be submitted to the action of the silent discharge at — 23°, and be slightly compressed, the gas acquires a deep blue colour, and after a time a blue liquid is produced. At — 88° the liquid is very dark blue. When carbon dioxide is decomposed by the electric spark at — 23° a blue gas is produced, and at a certain pressure (exact pressure is not mentioned) the undecomposed carbon dioxide condenses to a blue coloured liquid. By this experiment the authors think they have proved that ozone is one of the products of the decomposition, by the spark, of carbon dioxide.