"The upper part, or deoxidizer, is supported on a strong mantel plate resting on four cast iron columns. "The retorts and flues are made entirely of fire-brick, from special patterns. The outside is protected by a wrought iron jacket made of No. 14 iron. The puddling furnace is of the ordinary construction, except in the working bottom, which is made longer to accommodate two charges of ore, and thus utilize more of the waste heat in reducing the ore to metallic iron. "The operation of the furnace is as follows: The pulverized ore is mixed with 20 per cent. of pulverized charcoal or coke, and is fed into an elevator which discharges into the hopper on the deoxidizer leading into the retorts marked C. These retorts are proportioned so that they will hold ore enough to run the puddling furnace 24 hours, the time required for perfect deoxidation. After the retorts are filled, a fire is started in the furnace, and the products of combustion pass up through the main flue, or well, B, where they are deflected by the arch, and pass out through suitable openings, as indicated by arrows, into the down-takes marked E, and out through an annular flue, where they are passed under a boiler. "It will be noticed that the ore is exposed to the waste heat on three sides of the retorts, and owing to the great surface so exposed, the ore is very thoroughly deoxidized, and reduced in the retorts before it is introduced into the puddling furnace for final reduction. The curved cast iron pipes marked D are provided with slides, and are for the purpose of introducing the deoxidized ore into the second bottom of the furnace. As before stated, the furnace is intended to accommodate two charges of ore, and as fast as it is balled up and taken out of the working bottom, the charge remaining in the second bottom is worked up in the place occupied by the first charge, and a _new_ charge is introduced. As fast as the ore is drawn out from the retorts the elevator supplies a new lot, so that the retorts are always filled, thus making the process continuous." The temperature of the charge in the deoxidizer is from 800 deg. to 1,000 deg. F.--_Amer. Engineer._ * * * * * SOME REMARKS ON THE DETERMINATION OF HARDNESS IN WATERS. By HERBERT JACKSON. Having had occasion some short time ago to examine a hard water which owed half its hardness to salts of magnesium, I noticed that the soap test, applied in the usual way, gave a result which differed very much from that obtained by the quantitative estimation of calcium and magnesium. A perfectly normal lather was obtained when soap had been added in quantities sufficient to neutralize 14 deg. of hardness, whereas the water contained salts of calcium and magnesium equivalent, on Clark's scale, to a hardness of 27 deg..