2694. PIETERS, H. A. J. (50% each to C. Otto & Co. G.m.b.H. and Staatsmijnen in Limburg). Purifying Gases Such as Those From Coal Distillation. United States Patent 2,169,282, Aug. 15, 1939. Chem. Abs., vol. 33, 1939, p. 9601.

Describes arrangement of apparatus and a method of separating H2S from gases, which involves washing the gases with an aqueous ammoniacal solution initially containing Fe ferrocyanide in suspension and having an ammonium-salt content required to stabilize said ferrocyanide suspension against decomposition, regenerating the solution following its use and preparatory to its reuse in the washing operation by aerating the same, and compensating for the wastage of Fe ferrocyanide from the solution by adding to it finely divided material from the group consisting of (1) Fe ferrocyanide and (2) cyanides and Fe salts.