620 MODERN GASWORKS PRACTICE
carbonate, by the absorption of carbon dioxide, is converted into the bicarbonate, and when the solution of the latter is boiled, the salt is reconverted into the simple ■carbonate, carbon dioxide being expelled. The potassium carbonate solution acts, therefore, in a contimious cycle. After being saturated with carbon dioxide in the washers, it is deprived of it again by boiling, cooled, and sent back to the washers. The removal of C02 in this way is necessary, otherwise the remainder of the process for the extraction of the sulphur compounds is rendered inefl'ective. The carbon disulphide is taken up by the “ Atliion ” material, which is an alkalinated cellulose —that is, a compound of alkali and cellulose, obtained by treating cellulose siilphite with soda lye. The material thus produced is subjected to rolling and crumbling, afterwards being spread on purifier grids in the ordinary männer. The carbon disulphide, on combining with the material, then converts it into xanthogenate of cellulose (viscose), the latter product being of use in the manufacture of non-inflammable celluloid. The inventars claim that with. English coal the sulphur compounds are reduced from 30-75 to 7-87 grains per 100 cubic feet, or a reduction of 75 per cent. Ten tons of the special material absorb tons of carbon disulphide, and it is thus calculated that 10 tons would purify 35,000,000 cubic feet of gas.