William Wigeton, of New York City, has taken measures to secure a patent for improvements in the above. The purification of the gas is effected by passing it over the surface of a liquid, and is chiefly intended to be used for the extraction of the sulphurous impurities by washing in ammoniacal liquor, either at the bottom of the dry lime purifier or in a distinct vessel; this is performed by distributing the gas, in thin streams, over the surface of the liquor, and for this purpose the inventor employs a "scrubber," which is a float of wood or of some buoyant material, to keep on the surface, of a corresponding shape with the vessel in which the purifying liquor is contained, and having an opening in the centre. On the inside it is rather concave, so as to forma cavity, and is perforated with a number of passages, by which the gas is conducted to the outside. The gas enters this cavity from an inlet pipe, and by its expansion raises the " scrubber," which is partly submerged in the liquid, so that a portion of each opening is slightly elevated above the surface, through these it essapes in a number of very thinly-spread streams over the surface of the liquor upon which it is washed or scrubbed.