the author of this article had been collaborating with Andr6 Riband in the production of xenon and krypton from liquid air residues. These gases are acquiring importance in the technique of radiology. Since they occur to so small an extent in air, it is from the final evaporation of liquid oxygen that they are to be obtained. The process employed had been followed fifty times in more than one laboratory. Standing beside a container in which oxygen was evaporating, )fr. Ribaud was so badly injured by an explosion of the apparatus that he died, in a few llours. The Government of France conferred upon him posthumously the cross of the Legion of Honor.
Such accidents, says the writer, are by no means unknown in the oxygen industry. " Without apparent cause after months or years of perfect operation an apparatus explodes, sometimes very violently." He attributes them in general to the accumulation of impurities from the large quantity of air liquefied. " No matter to how small an extent a gaseous impurity is present in the air treated, if it can be condensed by intense cold and if, further, it is much less volatile than oxy.gen, it collects in the bottom of the apparatus through evaporation. If, in addition, this impurity is combustible, all the conditions for a violent explosion are present by a singular fatality. Now such is the case with acetylene in particular." With the plant treating moo cu. m. of air per hour throughout a month, one part in a million of acetylene would result in the storing of 4 kg. of a very violent explosive. It may be that ozone acts as the detonator, for the author has found it to react with solid acetylene, or perhaps electric sparks due to the evaporation of the liquid oxygen are to blame. In any case the air condensed should be as pure as possible and the part of the apparatus containing the accumulated impurities should be buried in the earth.
G.F.S.