524 



METALLURGY. 



iron approximates more closely to a tri- silicate 

 than to a bi-silicate, alumina being regarded as 

 a base. After the pig-iron has been charged 

 into the converter, it is blown for a few min- 

 utes, till the blue flame appears that marks the 

 beginning of the combustion of the carbon. 

 The blow is then stopped, and a definite pro- 

 portion of the charge the slag being removed, 

 containing usually 4'15 per cent, of carbon, 

 0'05 of silicon, and 0'07 of manganese is 

 poured into a measured ladle. The portion of 

 metal remaining in the converter is then blown 

 until most of the carbon has been eliminated 

 and the bath converted into malleable iron. 

 The metal previously removed, and what more 

 may be needed, is then added to the bath. 

 When the reaction that ensues is ended, the 

 metal is ready for pouring. 



A number of improvements, designed to se- 

 cure increased economy and greater efficiency 

 in working, in the production of basic Siemens 

 steel, have been introduced in a new furnace 

 recently erected at Bilston, South Staffordshire. 

 A rectangular furnace with rounded ends takes 

 the place of the old round furnace, producing 

 a longer flame, which seems to have a less de- 

 structive cutting power upon the lining and 

 upon the gas and air ports. The roof and part 

 of the internal side-walls are built of silica 

 bricks, and the bottom is lined with basic 

 bricks of exceptional density, which are sepa- 

 rated from the silica work with a chrome 

 brick. The roof is fixed instead of being 

 movable as before, the movable roof having 

 been designed, in the first place, to enable the 

 repairs to the interior of the furnace to be 

 more easily made ; but it was found in practice 

 that this advantage was more than lost by the 

 destruction that ensued to the roof by removals. 

 The repairs are now provided for by building 

 the case of the furnace, instead of solid steel 

 plates, of lattice-work, with silica brick-work 

 inside, which can be removed when repairs are 

 necessary. Three doors are provided in front, 

 and one at the back, over the tapping-hole. 

 The regenerative capacity of the furnace is 

 doubled, in the same space, by making the 

 regenerators rectangular, with rounded ends. 

 This is effected by the lengthening of the flame, 

 whereby the heat that formerly passed iuto the 

 chimney and was lost, is now all absorbed ; 

 besides which, it is possible to work with less 

 gas while obtaining a greater amount of heat. 



Mr. "W. Shimer, of Easton, Pa., uses for de- 

 termining phosphorus in steel the filtrate ob- 

 tained in the nitric and sulphuric method for 

 determining silicon; it has the desirable quali- 

 ties of being easily and quickly obtained and 

 always free from silica. In order, however, to 

 get all the phosphorus in a precipitable form, 

 the solution must be made under conditions 

 more strongly oxidizing than simple solution 

 in boiling nitric acid. It is found that in a so- 

 lution tlius made the presence of a moderate 

 amount of free sulphuric acid does not prevent 

 complete precipitation of the phosphorus. 



In H. Haupt's process for protecting iron 

 against corrosion, the pipes having been low- 

 ered into the retorts, the retorts are closed un- 

 til the contents are heated to a proper temper- 

 ature. Steam from a boiler at 60 pounds press- 

 ure is then introduced into the superheater, 

 which it traverses, and from which it escapes 

 at the temperature of the iron upon which it 

 acts for about one hour. A measured quanti- 

 ty of some hydrocarbon is then admitted with 

 a jet of steam, which completes the process. 

 The protection afforded by this method is not 

 a mere coating, like paint, but is said to be an 

 actual conversion, to a greater or less depth, 

 into a new material. When properly treated, 

 this material does not seem to be detachable 

 by pounding, bending, rolling, or heating. The 

 process is claimed to possess advantages over 

 the Bower-Barff process in that it makes a 

 coating that does not crack, and is more re- 

 sisting. 



Prof. A. Ledebur has made a series of exper- 

 iments upon the effect of acidulated waters in 

 producing brittleness in malleable iron. The 

 brittleness arises from the absorption of hydro- 

 gen by the iron causing a change in its mechan- 

 ical properties, whereby, while the modulus of 

 tensile strength remains unaltered so long as 

 the metal is not sensibly corroded, the exten- 

 sion under stress and the capacity of resisting 

 bending strains are notably diminished. The 

 author also finds that an action similar to that 

 of weak acid is produced by the atmosphere 

 when iron is exposed to it in an unprotect- 

 ed condition. Contact of the iron with zinc, 

 which renders the former electro-negative, 

 proved to have a notable effect in increasing 

 the influence of the acid on the unprotected 

 portion of the surface, so that a very much 

 shorter time sufficed to produce brittleness 

 than without such contact. The brittleness 

 produced by pickling or rusting is removed by 

 annealing, and also disappears, or is consider- 

 ably diminished, by allowing the brittle metal 

 to rest for some time in a perfectly dry place. 

 It can not, however, be removed by mechanical 

 treatment in the cold. Cast-iron is not sensi- 

 bly, or is only slightly, affected by pickling. 

 Some direct determinations were made of the 

 hydrogen present in the brittle wires. It was 

 found to be so very minute as to raise a pos- 

 sible question whether it was sufficient to pro- 

 duce the remarkable changes in mechanical 

 qualities demonstrated by the experiments. In 

 considering this point, the author suggests that 

 the influence of a foreign substance upon iron 

 may be determined not so much by the weight 

 as by the number of the atoms present, and 

 therefore that hydrogen, whose atomic weight 

 is only ^ T that of phosphorus, the element 

 which it most nearly simulates in effect, may 

 be sufficient to produce very decided brittle- 

 ness, even when present in scarcely appreci- 

 able quantity. 



Aluminum. Comparative tests of aluminum 

 and magnesium have been made at the labora- 



