The general plan of the open-hearth process was certainly conceived by Josiah Marshall Heath in 1845, if not indeed by Reaumur in 1722, but for lack of a furnace in which a high enough temperature could be generated it could not be carried out until the development of the Siemens regenerative gas furnace about 1860.
In the regenerative system of firing, a mixture of carbon monoxide and nitrogen is produced by passing air through incandescent gas coke in a generator placed below the bench of retorts, and the heating value of the gases so produced is increased in most cases by the admixture of a small proportion of steam with the primary air supply, the steam being decomposed by contact with the red-hot coke in the generator into water gas, a mixture of carbon monoxide and hydrogen (see Fuel: Gaseous).
All these institutions are performing a great regenerative work, and the tribulations and disappointments of the last decades of the 19th century were not all loss.
In the intermittent system the waste heat can, it is true, be utilized either for raising steam (but inefficiently and inconveniently, because of the intermittency), or by a regenerative method like the Siemens, Fig.
Heated by gas, with regenerative checker work at each end, and fed with ore or concentrates, red-hot from the calciners, through a line of hoppers suspended above the roof.
Mention must be made, however, of an author whose work connects the literature of the Adriatic Servians of the 18th century with the regenerative efforts of the Danubian Servians in the second decade of the 19th century.
The fusion of sheet-glass is now generally carried out in gas-fired regenerative tank furnaces.
These small furnaces are frequently arranged for direct coal firing, but regenerative gasfired furnaces are also employed.
In their place the regenerative stoves of the Whitwell and Cowper types (figs.
The injury which initiates them may be very slight in the first placea mere abrasion, puncture or Fungus infectionbut the minute wound or other disturbance, instead of healing over normally, is frequently maintained as a perennial source of irritation, and the regenerative tissues grow on month after month or year after year, resulting in extraordinary outgrowths often of large size and remarkable shape.