MECHANICS AND USEFUL ARTS. 47 



BEDUCTION OF CAST IRON BY SUPERHEATED STEAM. 



The following account of some highly interesting experiments on the 

 decarbonization of cast iron by superheated steam, is reported to the 

 Scientific American by the experimenters, Messrs. Dufficld and Hart 

 of Detroit, Michigan. 



They state that during the past year they commenced a series of 

 experiments upon the action of superheated steam upon the quality of 

 iron, with thu lollowing points in view: 



1st. To see whether superheated steam could be used in the place of 

 air, for the decarbonization of the iron. 



Jd. If the chemical interchange would set in between the hydrogen 

 of the superheated steam and the sulphur, in combination with the 

 iron, to form sulphuretted hydrogen gas, thus freeing the iron from 

 such a deleterious substance, and correct perfectly what is technically 

 known as red shortness. 



3d. To see if the oxygen, if liberated, would unite with the carbon 

 in the iron, producing an intense combustion as much increased in in- 



If 



superheated steam process was successiui, it would do away wi 

 the blowing engine, as the pressure would be derived direct from the 

 boiler, thus economizing the expense of the engine, and the cost for 

 attendance, &c. 



As this matter was solely theoretical, and we could not say how it 

 would act until fairly tried, apparatus was devised for testing the 

 matter thoroughly by experiment. This consisted of a coil 34 feet 

 long, pipe, coiled within a foot circle. Around this was built 

 a furnace, where a bright red heat could be brought upon every 

 portion of the coil, by means of charcoal ; the furnace was connected 

 with the main boiler in the laboratory, by a pipe, in such a way that 

 the condensed steam would not have to traverse the coil. From the 

 coil the pipe led to a Sefstroms furnace driven by a fan, containing a 

 crucible holding a sufficient quantity of molten cast iron, combined 

 with a large proportion of sulphur. Into this, while in a liquid state, 

 with steam at a temperature of 1,200 Fahr., the tuyere at the end of 

 the steam pipe, transmitting the superheated steam, was lowered into 

 the metal. We were disappointed that the molten iron did not evolve 

 gases, and burst into vivid combustion. AVe were aware that ordina- 

 rv steam cooled the metal, and therefore was inapplicable for use 

 in the temperature of iron ; but we had hoped this might be due to the 

 ordinary aqueous vapor carried forward in the swift mechanical cur- 

 iv:H of the steam, and thought if we could deprive the steam of its 

 moisture, that is, make a perfectly dry steam, that this objection 

 would cease. Such proved to be by our experiments a false deduc- 

 tion, for so soon as steam was introduced, the molten metal passed in- 

 to a semi-fluid and then a solid state. When the steam was first brought 

 in contact with the metal, the iron had the appearance of boiling 

 and was rapidly chilled. As no vivid combustion set in, we consid- 

 ered that it was due entirely to the mechanical displacement under the 

 force of steam. We read in text-books that iron at a red heat decom- 

 poses water. We have not succeeded in proving this decomposition 



