METALLURGY. (COPPER, STROimrM, ALLOYS.) 



477 



and has devised methods for saving in the wear 

 and tear of the apparatus. The possible appli- 

 cations of aluminum are innumerable ; and the 

 supply in our clays and earths being inex- 

 haustible, if the commercial manufacture is 

 made a fact, a new metal will be furnished to 

 the uses of man equal in economical value to 

 any that is now known. 



M. Bourbourze has found a means of solder- 

 ing aluminum satisfactorily. He uses alloys of 

 tin and zinc, or of tin, bismuth, and aluminum, 

 but one of tin and aluminum yields the best 

 results. The proportions of the alloy vary 

 with the kind of work it is intended for. 



Prof. Jamieson, of Glasgow, has found that, 

 with nearly pure aluminum, having a density 

 of 2'786, the electric resistance is 1'96 times 

 that of pure copper wire of the same length 

 and diameter. For wires of equal length and 

 weight the resistance of aluminum is a little 

 less than that of pure copper. The addition 

 of a small quantity of aluminum to copper 

 largely increases both the mechanical and the 

 electrical resistance. The first experiments 

 furnished specimens in which the electrical 

 resistance was twenty-five times as great as 

 that of pure copper. 



Copper, Prof. T. Egleston, of New York, has 

 observed the presence of tellurium in samples of 

 black oxide of copper and of pig-copper from 

 Colorado, which had the effect of " poisoning " 

 the metal and rendering it unfit for refining. 

 His analyses showed no antimony or arsenic, or 

 only a very minute quantity of the latter metal 

 in one specimen, but revealed the presence of 

 from 0'083 to 0*12 per cent, of tellurium. In 

 the laboratory, when the metal was " dry- 

 roasted," very dense white fumes were given 

 off. When refined and cast into a cake, the 

 metal had the ordinary appearance of cake- 

 copper. It was then reheated for rolling in 

 the ordinary way, without showing any signs 

 of impurity. At the first pass in the rolls, 

 however, very fine cracks showed themselves, 

 which opened in succeeding rolls. At a thick- 

 ness of about 0*03 of a metre, the cracks on 

 each side nearly penetrated the cake, and at 

 about 0-008 of a metre it began to fall to pieces. 

 When cold, the metal is tough and malleable. 

 Although the cakes in the molds showed no 

 coating, when they were > heated repeatedly, 

 and allowed to cool in tlie air, they became 

 covered with a white powder, which proved 

 to be oxide of tellurium. This is believed to 

 be the first time the presence of tellurium has 

 been detected in commercial copper. It is 

 worthy of remark how small a quantity of this 

 impurity renders the copper red - short, and 

 consequently worthless for rolling. 

 ^ Strontium. The recent introduction of stron- 

 tium into the manufacture of tuyeres has given 

 considerable importance to the minerals of that 

 earth, which are comparatively scarce. The 

 ore, celestine, a sulphate, is worked at Favara, 

 near Girgenti, in Sicily, whence it is shipped 

 to Hamburg and other ports. The rate at 



which the working is being developed may be 

 estimated from the fact that while only 1,000 

 tons were exported in 1880, 4,000 tons were 

 sent away in 1881. Works for the conversion 

 of the Sicilian ore into caustic strontium, or 

 the carbonate (strontianite), have been built at 

 Kosslau, in Alsatia. 



Alloys. The investigation for the location of 

 the strongest of the bronzes that is, for ascer- 

 taining the precise composition of the strong- 

 est metal has been conducted in five succes- 

 sive stages: by Wertheim and Eiche in the 

 elasticity and tenacity of the alloys; Thurston 

 on the copper-tin alloys ; Thurston on the 

 copper-tin-zinc alloys ; Coster on the strong- 

 est bronze ; and, finally, up to the present 

 time, by W. Ernest H. Jobbins. The result 

 in each of these investigations has been to con- 

 firm the conclusions reached in the previous 

 ones, and define them more precisely. Thurs- 

 ton determined of the copper-tin alloys that, in 

 those containing less than 20 per cent, of tin, 

 the strength and density were in a certain de- 

 gree dependent upon one another ; that the 

 maximum density was nearly approached in an 

 alloy 62'31 copper, 37'35 tin ; that the maxi- 

 mum of resistance to torsional and tensional 

 stress is reached in the alloy containing 82 '70 

 copper, 17'34 tin ; that ductility follows a reg- 

 ular law depending on the composition ; that 

 the resilience, or amount of work done in 

 breaking any specimen bears a close relation 

 tojhe ductility, the maximum torsional resili- 

 ence lying in a bar composed of 96 '06 copper, 

 3'76 tin, and a second maximum resting in'the 

 alloy 0-32 copper, 99'46 tin, while the resilience 

 diminished from both points to 35'85 copper, 

 73'80 tin ; and that the highest elasticity was 

 found in alloys containing between 25 and 35 

 per cent, of tin. 



Continuing his reseaches on the triple alloys, 

 Prof. Thurston constructed a relief-map on a 

 triangular base, in which the angles were de- 

 signed to represent the pure metals, or, respect- 

 ively, copper = 100, tiu = 100, zinc = 100 per 

 cent., while the various points in the area of 

 the triangle represented different proportions 

 of the metals, as determined by graduated 

 scales along the sides of the figure. When the 

 numbers representing the several properties to 

 be investigated, having been obtained by ex- 

 periment in the autographic testing-machine, 

 were entered in the triangular map, lines of 

 equal strength, of equal ductility, or of equal 

 resistance could be drawn, as, in topographical 

 work, lines of equal altitude are drawn, and 

 the map would become thus a useful representa- 

 tive of the valuable qualities of all possible al- 

 loys. At each point in this map representing 

 a certain alloy, vertical wires were fixed of a 

 length proportioned to the strength of the al- 

 loy, so as to produce a forest of wires, the tops 

 of which were at elevations varying with the 

 different qualities of the alloys to be studied. 

 The space was then filled with clay or plaster, 

 so molded as to leave the tops of all the wires 



