484 



METALS. 



treme, or wrought-iron, has its pyramids flat- 

 tened down to parallel surfaces or leaves, 

 which in their arrangement produce what is 

 called the fibre of the iron. The highest qual- 

 ity of steel has all its crystals in parallel posi- 

 tions, each crystal filling the interstices formed 

 hy the angular sides of its neighbors. The 

 crystals stand with their axes in the direction 

 of the pressure or percussive force exerted 

 upon them in working, and consequently the 

 fracture shows the sides or sharp corners of 

 the parallel crystals. In reality, good steel 

 shows, when examined under the microscope, 

 large groups of fine crystals like the points of 

 needles all arranged in the same direction 

 and parallel. 



Melting Steel easily. The Iron Age says 

 that the difficulty of melting steel in sufficient- 

 ly large mass for some purposes is well known, 

 as, hy the ordinary processes, owing to ex- 

 posure of the gases of combustion and other 

 causes, much deterioration of the quality is 

 almost sure to be the result. As a partial 

 remedy, the metal is usually melted in cruci- 

 bles, but these are expensive and require con- 

 stant renewal, and, when a heavy casting is to 

 be made, it is necessary to use a large number 

 of them, and it is difficult to regulate their 

 temperature so that all shall be at exactly the 

 proper melting-point at a given time. A Ger- 

 man founder recently announced a method 

 used by him, by which the difficulties men- 

 tioned above may be obviated, and steel in any 

 quantity melted and cast as readily as iron. 

 He dispenses with crucibles, and melts his 

 steel in a hearth of burned fire-clay, capable 

 of containing 1,800 pounds. The furnace is so 

 arranged that at the proper time a bellows can 

 be brought into play so as to bring the heat to 

 the melting-point in a very short time, and 

 thus avoid any continued strain upon the 

 hearth. To protect the melted steel against 

 the injurious influences of the gases of com- 

 bustion, it is covered with a coating, one or 

 two inches thick, of melted green bottle-glass, 

 or furnace-slag, made in a charcoal iron fur- 

 nace, great care being taken to exclude any 

 sulphur. About 70 pounds of glass or slag will 

 be needed for every 100 pounds of steel. If 

 one hearth will not hold enough steel, several 

 may be used. The melted metal is to be drawn 

 off in the usual way into kettles, lined with 

 clay, and transported to the mould for casting. 

 Bronze Guns. A government committee in 

 England have been investigating the merits of 

 bronze ordnance. They have found that, by 

 adopting a narrower groove than those in the 

 French pattern of large guns, and carefully 

 adjusting the height of the studs in relation to 

 the groove, such a piece will endure a great 

 amount of firing without becoming unservice- 

 able. The Engineer, referring to the work of 

 the committee, says : 



Two guns have, at the hands of the committee, en- 

 dured respectively 2,673 and 1,362 rounds with 

 charges relatively higher than those of any other 



rifled gun in Europe, and still remain perfectly ser- 

 viceable. These figures, translated into plain Eng- 

 lish, mean a life of 53 and 27 years' ordinary service. 

 It is clear, therefore, that bronze may be perfectly 

 serviceable for rifled field-guns. On the other hand, 

 it was urged that these results could only be ob- 

 tained by adopting very soft metal for the studs. 

 But, as General Wilmot's committee observes, " when 

 put to the test of experiment this objection is found 

 to be completely without foundation. The zinc studs 

 are but little liable to injury by the rough treatment. 

 Nothing short of intentional injury can render the 

 projectiles thus studded unserviceable." As to the 

 scoring of the grooves, from which much was feared, 

 the practice is not thereby materially aifected, the 

 scoring being confined to the loading side and bot- 

 tom of the bore. Further, when shells were burst 

 by the committee within the gun, the serviceability 

 of the weapon was not interfered with. But, for all 

 that, it is evident that if bronze can be made at once 

 harder, more resisting, and more elastic, it will be, 

 pro tanto, a superior metal for artillery purposes. 



White Brass. An alloy to which this name 

 has been given, and which differs from the 

 alloys commonly known as white metal (though 

 in what respect is not stated) is well spoken of 

 in English papers, in its application to journal- 

 bearings. It is said not to clog the file, and 

 to be susceptible of a high polish ; at the same 

 time its fusing-point is lower than that of or- 

 dinary brass, and it can be melted in a common 

 ladle on a stove-fire. It can also be cast in 

 metal moulds, or even in sand and loam, like 

 ordinary gun-metal. For axle-bearings on 

 railroads it has commanded approval on ex- 

 periment. According to a report of a trial of 

 the comparative merit of white brass and or- 

 dinary brass bearings on the Great Northern 

 Railway, it appears that two white brass bear- 

 ings, fitted under a break-van, lost only 2 

 ounces in weight in running 1 9,400 miles. Two 

 ordinary brass bearings, fitted under the other 

 end of the same van, and which travelled the 

 same distance, lost 2 Ibs. 4 oz. In another case 

 a third-class carriage was fitted up in a similar 

 manner, and ran 20,000 miles. Here the white- 

 metal bearings lost only 2J oz., while the ordi- 

 nary brass bearings lost 1 Ib. 6 oz. In another 

 third-class carriage, similarly fitted, the dimi- 

 nution in the white-metal bearings was 2J oz., 

 while in the ordinary brass bearings it was 

 1 Ib. 12 oz. in running 20,000 miles. The bear- 

 ings ran perfectly cool, and were lubricated 

 with oil. 



Copper in a Bird's Plumage. Prof. Church, 

 of England, is the authority for the state- 

 ment that traces of copper are found on the 

 feathers of the turaco, or plantain-eater, of 

 the Cape of Good Hope, a bird celebrated for 

 its beauty. He says that it is an essential in- 

 gredient in the composition of the red coloring 

 matter of the bird's plumage, constituting 

 about six per cent, of the same, and cannot be 

 removed from it without a destruction of the 

 matter ; in effect, all the ordinary means fail 

 to detect it without the pigment be first 

 destroyed and the ash then examined for the 

 metal. The existence of the red plumage is 

 dependent upon copper, which, obtained in 



