Dr. Schafhaeutl on the different Species of Cast Iron, %c. b'1\ 



contains more sulphur than the quantity mentioned by him. 

 Charcoal itself imparts a portion of sulphur to the iron. 



As a further proof of what has just been asserted, we now 

 refer to some specimens of French cast iron, the produce of 

 the furnaces near Alais, departement du Gard, at the foot of 

 the Cevennes. 



These specimens were produced from hydrated oxides of 

 iron, which cover the summits of several hills of limestone and 

 carboniferous sandstone extending over a long district, and 

 have undoubtedly been deposited in this state by water. The 

 greatest part of this ore has a perfectly ochry appearance, in- 

 termixed with masses of red oxide of iron, which is so similar to 

 oxide of iron, precipitated from its solution in acids hy caustic 

 ammonia, and dried on a filter, that it is impossible to distin- 

 guish between the two specimens when placed together, which 

 is the artificial and which the natural. As it is the mode in 

 France to assay the iron ores only in the dry "way in a small 

 crucible, lined with charcoal, nothing more is obtained than the 

 quantity of metallic iron which is contained in the ore ; and as 

 those ores were found to be very rich and in great abundance, 

 a large iron- work has in consequence been erected; but actual 

 trial of the ore in the blast furnaces very soon convinced the 

 proprietors, that in the selection of ore for practical purposes 

 more research is required than the mere melting down of three 

 grammes of iron ore in the crucible in the laboratory. 



The iron obtained from this ore had invariably the bad 

 quality of emitting a great quantity of fumes during heating, 

 and not welding except in a state of half-fusion. But when 

 this welding was accomplished, the iron naturally had lost its 

 quality, and was found to be burnt. This ore is invariably 

 mixed with a subarseniate of iron, which contains in 100 parts 

 7 of arsenic acid and 13*68 of water, and is mechanically mixed 

 with galena, bournonite, and similar minerals. The small 

 quantity of arsenic in this case is easily overlooked even with 

 the blow-pipe, and generally no other means will detect the 

 presence of arsenic except a current of sulphuretted hydrogen. 



The manner of conducting the blast furnaces with pit coal 

 in France is, notwithstanding the great difference in the ores, 

 exactly the same as in England ; and English workmen are 

 down to the present time generally employed, not only in work- 

 ing at the puddling furnaces, but also at the blast furnaces. 



It will be apparent, that the above-mentioned ore is ex- 

 tremely fusible, and requires therefore a very careful arrange- 

 ment of the fluxes, in order to obtain a tolerably good quality 

 of cast iron, particularly as in this hot southern climate the 

 rarefied and dry air has a peculiar influence on the produc-. 



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