1 87 1.] Metallurgy. 391 



ation continues to effect. In an introductory notice, the Honorary Secretary, 

 Mr. R. Hunt, F.R.S., sketches the rise and progress of the association, and 

 shows the part which it has played in supplying the working miner with 

 sound, scientific education. It is really vexing to learn that such good work 

 should be impeded by insufficiency of funds. The present report contains 

 papers on boiler explosions in Cornwall, by Mr. C. E. Martin ; on the use of 

 Haupt's improved rock-drill in Swaledale, by Sir G. M. Denys, Bart.; and on 

 a new buddle for dressing gold, tin, copper, lead, or other ores, by Mr. R. H. 

 Williams. 



A paper on the iron-producing districts of Central Sweden has been commu- 

 nicated to the Iron and Steel Institute, by Mr. David Forbes, F.R.S. The 

 disadvantageous inland position of these mineral deposits has hitherto im- 

 peded their development, but the construction of a railway traversing the 

 heart of these iron-mining districts will probably render them available to the 

 English iron-master, whilst a considerable impetus may be given to the iron- 

 trade of Sweden, which of late years has been decidedly on the wane. 



METALLURGY. 



Considerable discussion has lately arisen as to the value of the " Sherman 

 Process " for purifying cast-iron. The application of very small quantities of 

 iodine, or some compound of this element — such as potassic iodide — is said to 

 effect the removal of sulphur and phosphorus from the crude metal, so that 

 good wrought-iron or steel may be obtained from inferior brands of pig-iron. 

 Mr. Snelus, of Dowlais, has, however, examined samples of steel treated by this 

 process, and fails to detect any appreciable chemical difference between this steel 

 and that made by the ordinary method. In defence, Mr. Sherman has pub- 

 lished an analysis of a cast-steel said to have been made from Cleveland pig 

 by his process. It is well known that the Cleveland iron contains a large pro- 

 portion of phosphorus, but this is reduced to 0*04 per cent in the steel. The 

 following analysis is due to Mr. Barker, of the Atlas Works, Sheffield : — Com- 

 bined carbon, 0*67 ; graphite, traces ; phosphorus, 0*04 ; sulphur, traces. 



Mr. Bessemer suggests that if iodine is so efficacious in refining iron, it 

 would certainly be more economical to employ crude substances containing 

 iodine, such as vitrified sea-weed, than to use the element itself or its pure 

 compounds. 



Under the name of " Burnt Iron," our workmen recognise iron which has 

 been damaged by re-heating or by exposure to excessive heat after balling in 

 the puddling-furnace. Such iron is brittle, and having lost its fibrous cha- 

 racter, breaks with a short crystalline fracture. The cause of this change has 

 not hitherto been satisfactorily explained, but Mr. Mattieu Williams has pre- 

 sented to the Chemical Society a paper on this subject, in which he shows 

 that the burning of iron is simply a process of oxidation, which, however, 

 affects the whole substance of the metal. By working the iron in a reducing 

 atmosphere, this internal oxidation is prevented, and the various devices 

 employed by workmen to prevent burning are based upon this principle. 



Steel raised to a yellow or white heat and suddenly cooled, is rendered 

 permanently hard and brittle, and incapable of being tempered by simple 

 re-heating. This " burnt-steel " presents a coarse granular fracture, and 

 in addition to a crystalline structure shows certain rounded facets, with 

 concavities known as " toad's-eyes." The carbon in steel prevents the oxida- 

 tion which produces burnt iron ; but it is known that a slow combustion of the 

 carbon in steel may take place even at a low red heat, and that this action 

 gradually proceeds inwards. Mr. Williams believes that the carbon-monoxide 

 produced by interior oxidation may remain in occlusion in the iron, and that 

 if steel be suddenly cooled, so that this occlusion is prevented, the minute 

 bubbles of carbon-monoxide and oxygen thus arrested would render the steel 

 porous, and so affect the cohesion of its molecules in such a way as to produce 

 the characters of burnt steel. 



Herr H. Scheerer publishes in the " Berg- und Huettenmaennische Zeitung " 



