748 



STEM AN PROCESS, THE. 



convey tli.> selvage to and from the pumps, 

 and are built over each other to avoid the ex- 

 pense of separate foundations. 

 ' The course of the sewage is from the outfall 

 sewer along the low-level culverts to the 

 pumps ; thence to the reservoir along the high- 

 level culverts; and thence either to the low- 

 water outlets, or to the deep outlet, along the 

 middle-level culverts, into the river. In addi- 

 tion to the sewage which will accumulate in 

 the reservoir between the periods of discharge, 

 the reservoir will provide for storing rain to an 

 extent which probably will not be exceeded 

 more than a few days in the year, when the 

 overflow may take place at a less favorable 

 time of tide. In order to deliver the sewage 

 into the river under as favorable condition as 

 possible, the deep outlet is constructed with a 

 series of 12 iron pipes, 52in. in diameter, ex- 

 tending for a considerable distance under the 

 fore-shore. About 120 penstocks, or sluices, 

 are fixed in various places, nearly 100 of the 

 number being in the reservoir. For about 

 1,200ft. the river will be embanked by a retain- 

 ing wall of brickwork, built on caisson founda- 

 tions and capped with granite; the wall will 

 be backed up with concrete, and the reclaimed 

 ground filled in and levelled. The contracts, 

 both for the buildings and the engines, are in a 

 forward state, and it is hoped will be com- 

 pleted by the end of the year. Cottages will 

 be erected for a superintendent and a staff 

 of workmen, to reside at the works, so that 

 constant supervision and attendance may be 

 given. 



SIEMAN PROCESS, (Tnu). An invention 

 of vast importance to American mines and 

 manufactures has recently been introduced at 

 Pittsburg. After careful and thorough experi- 

 ments, its merits are now fully established. It 

 is essentially a new method of generating and 

 applying heat in the processes of metallurgy, 

 and is called the " Sieman Furnace." The in- 

 ventor is a German, residing in Great Britain, 

 where, as well as on the continent, the new 

 furnaces are being extensively and successfully 

 worked. The principle is applicable to all pro- 

 cesses of reducing, refining, and working metal- 

 lic ores, or metals, and, indeed, wherever heat 

 in large quantities is required. 



In furnaces of the old style, the solid fuel, 

 whether it bo wood, charcoal, peat, or pit coal, 

 is usually placed in immediate contact with the 

 material to bs heated. In the case of steel, 

 glass, zinc, etc,, the substances are enclosed in 

 retorts or pots to protect them. The Sieman 

 process makes a radical departure from the old 

 process at the outset. A "producer" (a re- 

 ceptacle of very simple construction) receives 

 the coal. It is converted into gas by slow com- 

 bustion, and conveyed through flues into the 

 furnaces, where the heat is required. Ilere it 

 combines with atmospheric air, and burns 

 rapidly, producing a degree of heat adequate to 

 all purposes required in the arts. This produ- 

 cer is of course entirely independent of the fur- 



nace. It may be of almost any conceivable 

 capacity, furnishing gas for one or any number 

 of furnaces. The gas producer of moderate 

 size is a chamber, say six feet by twelve, and 

 ten feet high. One of its end walls contains a 

 fire-grate reaching to half its height, inclined 

 at about such an angle as a heap of coals would 

 naturally take, say from 40 to GO degrees, ac- 

 cording to the quality of coal. 



The upper portion is inclined also, but is 

 made of solid iron plates, covered with fire- 

 brick. Stoppered holes are provided for the in- 

 troduction of an iron bar to break up the fuel 

 and detach clinkers. The fuel is introduced 

 through apertures above, which are usually 

 kept closed. It is introduced in small quanti- 

 ties, from time to time, as the supply is con- 

 sumed. The coal being ignited at the lower 

 portion of the grate, burns slowly under a mod- 

 erate draft, parting first with its most volatile 

 ingredients water, ammonia, etc., and yield- 

 ing hydro-carbon gases and some carbonic 

 acid. The combustion is now continued by 

 admitting a gentle current of air through the 

 grate. 



At the Iowa part of the grate carbonic acid 

 is formed of the union of the carbon of the coke 

 with the oxj'gen of the air. The gas ascends 

 through the heated mass above, and losing half 

 its oxygen, becomes carbonic oxide, a combusti- 

 ble gas of great heating value. The liberated 

 oxygen also combines again with carbon, pro- 

 ducing the same gas in equal quantity in its 

 turn. 



The atmosphere consists of about one part of 

 oxygen to four parts of nitrogen by weight. 

 The nitrogen is incombustible, and tends to 

 diminish the richness or heating power of the 

 other gases. In order to balance this loss and 

 secure oxygen in sufficient quantity, water is 

 brought in a small pipe and slowly introduced 

 at the bottom of the grate. The spare heat 

 converts it into steam, which, traversing the 

 burning mass of fuel, is decomposed by this 

 powerful heat into hydrogen and oxygen. The 

 latter forms carbonic oxide in the same manner 

 as the oxygen of the air, while the former is a 

 well-known combustible gas in its pure state. 

 Each cubic loot of steam thus produces as 

 much inflammable gas as five cubic feet of air. 

 This will be obvious when it is remembered 

 that water consists of eight parts of oxygen to 

 one of hydrogen, by weight. The generation 

 of steam being dependent upon the amount of 

 heat in the fire, regulates itself naturally to the- 

 requirements of the combustion. The total 

 production of the combustible gases varies, of 

 course, with the amount of air admitted ; and 

 since the admission of air into the grate de- 

 pends, in its turn, upon the consumption of the 

 gases evolved, the production is always regu- 

 lated by the demand in the heating furnaces. 

 The production of gas may be arrested for 

 several hours without deranging the process or 

 wasting the material. The mass rt the fuel 

 and the brick-work retain sufficient heat, dur- 



