480 



METALLURGY. 



tern for producing puddle-bar from iron which 

 has been put through the pneumatic process. 

 The melted iron is poured into the puddler, 

 which is a large cylindrical vessel so set that 

 it revolves. Heat from a Stubblebein furnace 

 is turned into the puddler, and as the iron be- 

 comes granulated it gradually takes the shape 

 of the vessel. After being puddled the metal 

 is compressed into billet- shape, and is then at 

 once reheated and rolled into bar or other iron. 



The magnetic iron-ore of Gellivara, Sweden, 

 according to the report of Mr. John Salt, gives 

 an average yield of 70-55 per cent, of iron. 

 The pig-iron produced by the smelting is very 

 tough and close grained, and appears to the 

 author very suitable for steel-making by the 

 Bessemer process, and for producing the finest 

 quality of forge-iron. 



By examining a very thinly-rolled plate of 

 steel from which the iron had been removed 

 by nitric acid, and only the carbon was left, 

 Messrs. Osmond and Worth, of Creusot, France, 

 have found that the carbon is not distributed 

 evenly throughout the mass, but that the steel 

 consists in its inner structure of tiny particles 

 of soft iron inclosed in cells formed by the car- 

 bon. These cells are again distributed in the 

 iron either combined or as a collection of cells 

 having considerable open spaces between them, 

 so that a plate or sheet of steel may be rolled 

 till it becomes transparent. These spaces mny, 

 in the raw material, be almost noticeable, but 

 are reduced by rolling and hammering. 



In the David Brose process for the improve- 

 ment of steel, which has been satisfactorily 

 tried at Pittsburg, a "purifier" a substance 

 that is plentiful and cheap is introduced into 

 the ladle immediately before the steel is run 

 in. The steel is then poured into the ladle 

 upon the purifier, when a violent reaction oc- 

 curs, setting free the contained gases, and caus- 

 ing a thorough agitation of the metal, with a 

 resultant commingling of the metal and man- 

 ganese more intimate than can be attained by 

 a mere mechanical mixer. The steel thus ren- 

 dered is claimed to be more uniform, and the 

 ingots are remarkably free from blow-holes. 

 By this process, steel of excellent quality can be 

 produced, it is said, with from 30 to 40 per cent, 

 less manganese than is ordinarily required. 



According to a testing made by Prof. W. F. 

 Barrett on a manganese steel containing from 

 12 to 14 per cent, of manganese, patented and 

 manufactured by Messrs. Hadfield & Co., of 

 Sheffield, the permanent magnetism of the ma- 

 terial was to that of steel of average quality as 

 20 to 100,000, and the induced magnetism to 

 that of iron as 300 to 100,000. In fact.it is 

 very wonderful, judging by muscular sense, to 

 find no sensible force required to move this 

 steel, even in the most powerful magnetic field 

 thatcould be obtained. Hence, it is suggested, 

 the use of manganese steel for the bed-plates 

 of dynamos and the plating of iron vessels, is 

 obvious. Ships built of such steel would have 

 no sensible deviation of the compass. Dr. 



Hopkinson has reached an accordant result 

 by a different method of interpretation. The 

 electric conductivity is also very low. The 

 hard wire has a tenacity of 110 tons per square 

 inch, and the soft wire of 48 tons per square 

 inch, with an elongation of nearly 20 per cent. 

 The modulus of elasticity was found to be 

 lower than that of wrought-iron ; so that, 

 though hard manganese steel- wire has an 

 enormous tenacity, it "gives" more than steel 

 tinder sudden stress, recovering itself if the 

 limits of elasticity are not passed. 



A method of -tempering watch-springs by 

 means of the electric current has been applied 

 by the Sedgwick Manufacturing Company, of 

 Chicago. The conductors from the dynamo 

 lead to a bench on which stands an ordinary oil 

 tempering bath. One of the conductors con- 

 nects with a point within the bath, and the 

 other with a point without. The piece of steel- 

 wire to be tempered is fed first under the con- 

 tact point on the outside of the bath, and then 

 under the point on the inside. When it has 

 reached the latter the circuit is complete, and 

 the wire at once becomes uniformly heated. 

 Since the variation in the percentage of carbon 

 in different pieces of steel forbids the delicate 

 process of tempering from becoming a purely 

 mechanical piece of work, the color of the 

 steel still has to determine the length of time 

 it shall be heated. The chief advantage claimed 

 for this process is, that the steel not having 

 time to oxidize after it has been heated to the 

 proper color before it is put under cover of the 

 oil, the wire is of the same thickness after it is 

 tempered as it was before it entered the pro- 

 cess. The uniformity of the heating through- 

 out the spring, the lessened liability to defect- 

 ive spots, and the rapidity of the heating four 

 inches of spring per second are claimed as 

 other advantages. 



The report of the first series of experiments 

 performed by the committee appointed by the 

 British Association to investigate the influence 

 of silicon on the properties of steel, has been 

 published. It summarizes the present state of 

 our knowledge on the subject as follows : 



1. Ingot iron. Silicon promotes soundness; 

 it resembles carbon in increasing the tenacity 

 and hardness; it should not exceed - 15 per 

 cent, if the metal has to be rolled ; and in some 

 cases it produces brittleness when cold. 2. In 

 steel-castings. Silicon promotes soundness ; it 

 is, however, regarded as a necessary evil, and 

 excess should be avoided, as tending to brittle- 

 ness and low extension ; about - 3 per cent, is 

 generally recommended. 3. In crucible steel. 

 A few hundredths per cent, is necessary to pro- 

 duce soundness. It is generally agreed that 

 considerable quantities of silicon may be pres- 

 ent without injury to the material. 4. Man- 

 ganese appears to be capable of neutralizing 

 the ill effect of silicon. The first series of ex- 

 periments was undertaken to determine the ef- 

 fect of silicon on the properties of specially 

 pure iron. The general conclusions were ar- 



