Industrial Manufacture of Krypton and Xenon.--(Engineerin~, Vol. CXLIV, No. 3745.) The utilization of krypton and xenon in incandescent lamps has for some time been looked upon as a very expensive practice, even though the emciency of the lamps would be much increased thereby. These gases are contained in air in very small quantities. Hundreds of millions of incandescent lamps are made annually, and the employment of krypton, even o11 a very small scale, would necessitate an annual production of several hundred cubic meters of the gas. It has been obtained as a by-product of the manufacture of oxygen and nitrogen but this method does not insure a sufficient supply. A process devised and patented by La Societe L'Air Liquide extracts krypton and xenon from the air, not as 1)yproducts but as main products, and in sufficient quantity to meet requirements. While, in order to obtain oxygen or nitrogen from the air it is necessary to liquefy the air completely, in extracting krypton and xenon it is only necessary to cool the air to the dew point and pass it through a rectification column in counter current to a very small quantity of liquid air. In practice the amount of washing liquid is of considerable importance but it is expected that improvements in the columns will allow the quantity to be reduced. The operation of the process is greatly facilitated by the employment of cold regenerators working alternately on the Frankl system. These regenerators render it possible to avoid pre-purification of the air (Drying and removal of CO2). Apparatus has been erected and undergone preliminary tests at the Boulogne works of the concern. It has a capacity of 3o,ooo cub. m. per hour of air compressed to o.7 arm. The energy consumption is estimated at 4o horsepower hours per litre of xenon and krypton mixed in the proportion on which the gases exist in the atmosphere. P,. H. ().