The average absorption for the first set of four analyses when three roasting-furnaces were discharging into the tower was 95 per cent. of the sulphuric acid, and that of the second set of four or five furnaces was 90 per cent. The amount of sulphuric acid charged per twenty-four hours was about 5,000 kilogrammes of 50 degrees Baumé, which flowed off with a density of from 56 to 58 degrees Baumé. The quantity of acid condensed varied according to the nature of the ores and the number of furnaces working. It ranged between 300 and 1,000 kilogrammes of 60 degrees Baumé per twenty-four hours. The condensation of anhydrous sulphuric acid would pay, according to estimates submitted by Herr Hasenclever; but to pass the gases through a tower filled with lime, in order to get rid of the remaining sulphurous acid, would prove too expensive at Stolberg. An attempt to use milk of lime proved partially successful; but it was not followed up, because it was decided to experiment with the process suggested by Prof. Cl. Winkler, of Freiberg, who proposes to pass the gases through a tower filled with iron in some suitable shape, over which water trickles. From the solution thus obtained, sulphurous acid pure enough to be used for the manufacture of sulphuric acid, sulphur, and a solution of green vitriol is made. Experiments with this process are making at Freiberg and at the Rhenania Works, near Stolberg. The trouble with the majority of methods thus far is, that the draught of the furnaces is so much impeded by the absorption towers that fans, blowers, or steam jets must be used to carry the gases through it. The experience of Herr Hasenclever has proved how difficult it is to find a satisfactory means of removing the noxious vapors from furnace gases without incurring too serious an expense. Thus far the value of the products obtained by absorption of sulphurous acid has not been equal to the cost of producing them. Herr C. Landsberg, who is general manager of the Stolberg Company, has had similar experience, though his experiments were made to test methods suggested at various times by Dr. E. Jacob and Dr. Aarland. Both are very ingenious, and were successful on a small scale, but failed when tried in actual working.--_Engineering and Mining Journal_. * * * * * NEW GAS EXHAUSTER. In common practice, the new exhauster at the Old Kent Road passes about five million cubic feet of gas per day of twenty-four hours, and requires the attention of two men and two boys for driving and stoking, at the following cost: s. d. Wages--2 men, at 5s. 6d 11 0 Wages--2 boys, at 3s. 6d 7 0 ----- £ 0 18 0 Oil, 1 gallon 0 3 6 Waste, 5 lb 0 1 0 -------- Total £ 1 2 6