METALLURGY. (!RON AND STEEL.) 



molecular transformation which takes place with 

 (.volution of heat, and when this molecular group- 

 in w is prevented by the presence of some other 

 body, the metal may be reduced to ordinary tem- 

 peratures without exhibiting magnetic phenomena. 

 Ferro-nickels are compared by the author of the 

 paper to solutions rather than combinations. It 

 is suggested that by the addition of nickel many 

 properties of steel may be studied at tempera- 

 tures considerably below those at which they 

 occur in pure steel. As an example are mentioned 

 the gradual changes of volume which take place 

 in the course of years, and which in the case of 

 nickel-steels may be observed at the temperature 

 of the laboratory; whereas it would be impossible 

 to study similar changes at an elevated tempera- 

 ture in pure steel. 



Treating of nickel-steel as used in commercial 

 work. H. F. J. Porter said at the autumnal meet- 

 ing of the Iron and Steel Institute that that metal 

 has a lower melting-point than ordinary steel 

 with the same carbon content. In the cooling 

 process, nickel tends to reduce segregation and 

 liquation, so that an ingot of nickel-steel is more 

 homogeneous throughout than one of simple steel, 

 and is less prone to form blowholes. Nickel-steel 

 in process of manufacture is very sensitive to 

 changes of temperature. Therefore, in forging or 

 rolling it, care must be taken to maintain a uni- 

 form temperature throughout the body of metal. 

 The tensile strength and elastic limit of this steel 

 are somewhat reduced by annealing, but are raised 

 by oil tempering to an extent beyond that to 

 which the annealing has lowered them. Forgings 

 of it are not hard to machine, but are exceedingly 

 tough. For ordinary forgings, nickel-steel of 

 from 3 to 3.5 per cent, of nickel and 0.25 per 

 cent, of carbon is used. It has from 20 to 30 

 per cent, greater elongation than simple steel of 

 about 0.50 per cent, carbon, with practically the 

 same elongation and reduction of area. Nickel- 

 steel forgings of high elastic limit are considered 

 best for service where rapid -alternations of ten- 

 Hile and compressive stresses are applied. Ordi- 

 nary steel corrodes about twice as much as nickel- 

 steel of the same carbon content on submersion 

 in salt water. Five per cent, nickel-steel with 

 1.25 per cent, of carbon, after oil tempering and 

 annealing, has an elastic limit of from 150,000 to 

 175,000 pounds per square inch, and is especially 

 serviceable for hydraulic cylinders, when very 

 high bursting pressures are applied. 



Gold and Silver. A perfected apparatus of 

 dry concentration, called the Crown concentrator, 

 i based upon the following mechanical princi- 

 ples: 1, That bodies of unequal size but equal 

 weights will fall together; 2, that bodies of equal 

 aize but unequal falling weights will not fall 

 together; 3, that the influence of specific gravity 

 upon a falling body increases or decreases pro- 

 portionately to the density of the medium trav- 

 ersed by the body; 4, that all mineral par- 

 ticles, however finely divided, will in falling, if 

 of equal size and left free to act, arrange them- 

 selves in accordance with their specific gravities. 

 The ore is crushed and then put through a series 

 of rolls gaged to give pulps of the necessary fine- 

 ness, and without reducing the sulfids to a slimy 

 poAvder. The pulp is then conveyed by a carrier- 

 belt to a sizer, where the particles are sorted ac- 

 cording to their fineness, and then to the con- 

 centrators, each load of particular fineness being 

 concentrated separately. Finally all the concen- 

 trates are delivered into one receptacle and all the 

 waste to one dump, unless for some particular 

 reason it should be desirable to deliver the par- 

 ticular sizes separately. 



At Mount Morgan, in Queensland, Australia, 

 the low-grade gold ores are extracted with a pre- 

 pared solution of chlorin in water, locally termed 

 " solution," and are not " gassed " as in the usual 

 methods. At the plant of the new West Works, 

 which deals with 100,000 tons per annum, the 

 chlorin is made from salt, dioxid of manganese, 

 and sulfuric acid. The gas from the stills is 

 dissolved in water trickling over pieces of glass, 

 etc., with which the towers are filled. The solu- 

 tion runs into the storage tanks, which are cov- 

 ered at the top and worked by pipes and valves in 

 the base operated from above. The vats have a 

 wooden perforated false bottom, and layers of 

 gravel and sand of diminishing size are laid upon 

 it. The ores are thrown into this bed and the 

 chlorin solution runs over it. The gold liquor is 

 drawn through and out from below by a small 

 vacuum of 5 pounds per square inch, and passed 

 on to the storage tanks. Fresh chlorin solution is 

 run in until the exit liquor contains plenty of 

 chlorin, when the ore is washed through with 

 water. The gold is precipitated by passing the 

 liquor through a 2-foot bed of crushed charcoal, 

 lying on a cloth on the wooden perforated false 

 bottom of the filtering vat, the charcoal being 

 afterward burned and the ashes smelted for the 

 metal. An extraction of 92.06 per cent, was 

 shown. The richer sulfid ores, which contain 

 about 4 ounces of gold -to the ton at the top 

 works, are, after they have been roasted, treated 

 by the same process, and they then show an 

 extraction of about 95 per cent. 



In the extraction of gold from its ores by means 

 of the battery amalgamating process, electro- 

 silvered plates have replaced in most instances the 

 plain amalgamated copper plates, since the latter 

 become more or less tarnished with copper salts, 

 which prevent amalgam or quicksilver from ad- 

 hering. Attention is called by J. R. Cooper to the 

 fact that all copper contains more or less cuprous 

 oxid, and that, as this oxid does not combine with 

 mercury, a plain copper plate can be only imper- 

 fectly amalgamated. Even if at first the whole 

 plate is coated with quicksilver, this will break 

 off from the oxidized parts, and the latter will be 

 exposed to the action of water, oxygen, carbonic 

 acid, etc. 



The tailings coming from mills which leach 

 gold ores with potassium cyanid always retain 

 more or less gold, and usually at least one-quarter 

 of the potassium cyanid and more or less free 

 caustic alkali per ton. H. M. Crowther finds that 

 if care is taken to add to the last wash water 

 from one to several pounds of caustic alkali, the 

 tailings will retain sufficient alkali to protect 

 the residual potassium cyanid and allow it to 

 have its solvent effect upon the residue in the tail- 

 ings, which are being slowly affected by the action 

 of air, moisture, and warmth. 



To the millman considering the expediency of 

 using electro-silvered plates in gold milling in 

 preference to plates of copper, the important ques-' 

 tion, Mr. Edward Halse says, is whether the sil- 

 vered plates extract more gold from the crushed 

 ore than the copper ones do. The author is con- 

 vinced from his own experience that this is the 

 case, and that silvered plates therefore should 

 supersede plain copper plates in this work; and 

 he offers many tables of results in support of 

 this view. In the discussion that followed the 

 reading of Mr. Halse's paper, it was pointed out 

 that in many cases the percentage of gold ob- 

 tained was low 7 in consequence of the failure of 

 the millman to keep his plates clean; and the im- 

 portance of the use of " elbow-grease " rather than 

 chemicals was strongly emphasized. 



