500 



METALS. 



pended in water undergoes a rapid motion 

 under the influence of a strong induction-cur- 

 rent, forming threads which spread out from 

 the cathode to the anode plate. 



New Method of obtaining Copper from Copper 

 Pyrites. A new process of obtaining copper 

 from copper pyrites with the aid of two waste 

 products is offered by Mr. H. M. Wilson. First, 

 burnt ore from the pyrites kilns is treated with 

 waste chloride of manganese liquor from the 

 chlorine stills, which is pumped on to a layer of 

 the ore several successive times. Much of the 

 copper in the ore is thus extracted by the free 

 acid always present in the still liquor. The chlo- 

 ride of copper solution is then run on to a suffi- 

 cient quantity of soda- waste to convert the 

 whole of the copper into sulphide by means of 

 the sulphureted hydrogen disengaged from the 

 waste. The manganese and calcium salts now in 

 solution can easily be separated from the sul- 

 phide of copper, which is thrown on to a drainer, 

 well washed, and afterward heated on iron 

 plates in order to convert it into sulphate of 

 copper, which is then treated with boiling 

 water and allowed to crystallize. At chemical 

 works, where the chloride of manganese liquor 

 is treated according to Weldon's method, a mod- 

 ification of the above would be necessary, as 

 that liquor could not in that case be employed. 

 The burnt ore might be ground fine and cal- 

 cined with common salt in a blind roaster 

 furnace, and then, after separating the copper 

 chloride by lixiviation, the treatment continued 

 as above described. 



The pyrites used in charging the burners for 

 the above process should be treated in the fol- 

 lowing manner: The large lumps are crushed 

 in a stone-crushing machine, and the dust and 

 smaller portions sieved away from the larger 

 pieces, which are then ready for use. The dust 

 and smaller lumps are ground into a paste with 

 water, spread on iron plates, and allowed to 

 dry at a gentle heat. Before the mixture of 

 pyrites and water is dry it can be marked out 

 into the required size for charging the kilns, 

 viz., about two inches square. The sulphur ore 

 thus prepared has the advantage of being uni- 

 form in size, of burning spontaneously as it 

 were, no additional heat being required to de- 

 compose it when once the burners are red-hot, 

 and of costing no more to obtain it in that form 

 than by adopting the ordinary process of break- 

 ing the large lumps with hammers. 



A modification of the process described is 

 being carried on on a small scale ; but it is not 

 generally known, or it would be extensively 

 adopted, owing to the simplicity and efficiency 

 of its nature. 



Increasing the Elasticity of Metals. Ucha- 

 tius's invention of " steel-bronze " cannon rests 

 on the observation that " all metals lead and 

 zinc excepted gain an increase of elasticity, 

 after undergoing a continuous weighting above 

 their first limit of elasticity." Later experi- 

 ments by the inventor of the steel-bronze can- 

 non appear to show that even homogeneous 



bronze is capable of a great increase of its 

 elasticity, through simple stretching without 

 condensation. It is only a stretching of the 

 metals beyond their limit of elasticity, whereby 

 the molecules, brought to a state of flow, glide 

 over each other, and assume a wholly new po- 

 sition, more favorable to resistance, that causes 

 the increase of elasticity. A simple condensa- 

 tion produces merely an increase of the abso- 

 lute solidity and diminution of the tenacity, 

 but no real increase of elasticity. The limit 

 of elasticity may be raised nearly to the break- 

 ing consistence, so that, in many cases, it is six 

 and seven times the original. Mere stretching 

 for a short time is of little use ; the tension 

 must last a considerable tune. It is also well 

 to apply a gradually-increasing weight. 



New Method for Toughening and Hardening 

 Copper. In order to add hardness, toughness, 

 and homogeneity to copper and copper alloys, 

 Mr. W. E. Everett, of Birmingham, takes ox- 

 ide of manganese preferably the black oxide 

 in a state of fine powder, in the proportion of 

 from 1 to 6 parts by weight to 100 parts of the 

 copper or the alloy to be operated on. He 

 puts the two together into the melting-pot, and 

 when the copper is melted, stirs the oxide of 

 manganese well into it. When the dross and 

 scum have risen to the surface, the copper or 

 alloy is ready to be poured into moulds. In 

 treating brass he proceeds as described with 

 respect to copper, adding the required percent- 

 age of zinc to the melted copper. The alloys 

 of copper to which the invention is specially 

 applicable are alloys of copper and zinc, but it 

 may be applied to all alloys of which the essen- 

 tial metal is copper. Besides rendering copper 

 and alloys of copper tougher, harder, and more 

 homogeneous, the treatment described facili- 

 tates the rolling of alloys of copper at a red 

 heat, and thereby effects an economy of time 

 and labor in the rolling process. Copper and 

 brass treated according to the invention are 

 admirably fitted for the manufacture of steam 

 boiler-tubes, bearing shafts or axles, axle-boxes, 

 sheathing for ships, and bolts and nails for the 

 same, as well as for sheet-brass and brass-wire. 

 Although in practice he has found the native 

 black oxide of manganese to answer well, yet 

 he does not limit himself to the use of that 

 particular compound of manganese, as other 

 oxides of that metal, or compounds which on 

 being heated yield oxide of manganese, may be 

 employed with like results. 



Wearing Qualities of Aluminium. The 

 comparative resistance of aluminium to change 

 of color and wear, when brought into daily use, 

 has been made the subject of observation by 

 Dr. C. Winkler, who finds that it is inferior to 

 silver in retaining color and lustre, being 

 about on a par in that respect with German 

 silver; while it wears more rapidly than sil- 

 ver, but less rapidly than German silver. 

 Spoons made of all three materials, each hav- 

 ing exactly the same weight, were used a 

 year under precisely similar conditions, being 



