321,390. National Processes, Ltd., and Gyles, T. B. July 27, 1928. Sulphur dioxide; sulphur trioxide. - Sulphur compounds are removed from gases particularly those too poor in sulphur for sulphuric acid manufacture by passage through or over moistened sintered or porous granular or agglomerated material, obtained by blast roasting ores such as zinc sulphide ores. The sintered material after use may be mixed with fresh batches of ore and returned to the roaster, or may be leached for the extraction of sulphates and sulphites. The gas may be passed into the centre of a heap of moist sintered ore, or the sintered ore may be placed in a tower down which water flows to leach out the sulphates and sulphites continuously. Specifications 306,569; 306,787, [Class 82 (i), Metals, Extracting &c.]; and 307,439 are referred to.