8721. Westdeutsche Thomas-phosphat- Werke Ges. April 7, [date applied for under Patents Act, 1901]. Gases, treating electrically; nitrogen oxides, acids, and salts.-In the production of oxides of nitrogen by means of the electric arc, an increased yield is obtained by reducing the pressure both in the arc chamber and in the absorption apparatus connected thereto. When, instead of water, soda lye, or limewater, absorbing-solutions are used which give off gases under the action of the nitrogen oxides, e.g. common-salt solution, further absorption vessels are added containing liquids, such as water or milk of lime, which rapidly absorb the hydrochloric acid or other gas evolved, and so keep up and increase the vacuum in the apparatus. Any nitrous acid remaining can be oxidized to nitric acid by so arranging the apparatus that untreated air can be led in through the arc chamber to the other vessels, after stopping the electric current.