METALLURGY. 



481 



rived at from the results that on adding sili- 

 con in the form of silicon peg to the purest 

 Bessemer iron, the metal is quiet in the mold 

 even when only a few hundredths per cent, of 

 silicon is added. The metal is originally red- 

 short, especially at a dull-red heat, though it 

 works well at a welding temperature ; the red- 

 shortness being increased by silicon. In all 

 cases examined the metal was tough, cold, 

 and welded well, the silicon having little or no 

 influence. Silicon increases the elastic limit 

 and tensile strength, hut diminishes the elonga- 

 tion and the contraction of area a few hun- 

 dredths per cent. The appearance on fracture 

 by tensile force is changed from finely silky 

 to crystalline, while the fracture produced by 

 a blow gradually, as the silicon increases, be- 

 comes more like that of tool-steel. The hard- 

 ness increases with increase of silicon, but 

 appears to be closely connected with the te- 

 nacity. With - 4 per cent, of silicon and 0'2 

 per cent, of carbon, a steel was obtained diffi- 

 cult to work at high temperature, but tough 

 when cold, capable of being hardened in water, 

 and giving a cutting-edge which successfully 

 resisted considerable hard usage. In some 

 cases silicon was present in the oxidized con- 

 dition. The effect is then very different, and 

 the mechanical properties of the metal more 

 nearly resemble those of the original Bessemer 

 iron. In the second series of experiments 

 various proportions of silicon have been added 

 to ingot metal, containing manganese and car- 

 bon as ordinarily met with in commerce. The 

 results are not yet quite ready for publication, 

 but they show that manganese greatly modifies 

 the effect of silicon in producing redshortness, 

 and hence enables the metal to be rolled and 

 otherwise worked, even in the presence of 

 several tenths per cent, of silicon. The low 

 extension, however, though not nearly so 

 marked as before, is still observed, despite the 

 presence of manganese; and hence, for the 

 majority of the applications of mild steel, sili- 

 con does not appear to be advantageous. 



In experiments upon the behavior of pigs of 

 iron containing very little silicon and varying 

 proportions of phosphorus and manganese, 

 when heated in wood-charcoal, nine test pieces 

 were packed separately, amid small fragments 

 of charcoal, and heated to about 1,000 C. for 

 108 hours. On examining the samples it was 

 found that in all the malleable irons the per- 

 centage of carbon had increased, while in other 

 specimens there was a diminution in the amount 

 of carbon. 



It has been decided by the Supreme Court of 

 Pennsylvania that, in the absence of anything 

 showing the contrary, a grant of the right to 

 mine and carry away iron-ore must be held to 

 apply only to such ore as can be employed in 

 the manufacture of iron as ordinarily car- 

 ried on ; and that it does not necessarily in- 

 clude all substances containing iron, and capa- 

 ble of being made to yield that metal ; but only 

 such as are commonly used for that purpose. 

 VOL. xrvii. bl A 



An earth containing a percentage of iron too 

 small to be profitably smelted, and suitable only 

 for making paint, did not come within the 

 terms of such an agreement. 



Experimental tests have been made with the 

 malleable castings of Messrs. Michaelis and 

 Casparius, of Berlin, to determine the strength 

 of the materials, and of the articles manufact- 

 ured from them. One series of tests was car- 

 ried out with pieces in their ordinary condition, 

 11 -81 inches long and 1-58 inch by 0'24 inch 

 in section; while the second was made with 

 welded test pieces, as nearly as possible of the 

 same dimensions as those used in the first series. 

 The results were : in the first series, ultimate 

 tensile stress, 16'38 tons per square inch ; con- 

 traction, 8-2 per cent. ; extension, in a length 

 of 7'87 inches, 2'5per cent. ; limit of elasticity, 

 about 4/44 tons per square inch. Second series ; 

 ultimate tensile stress, 19 -24 tons per square 

 inch; contraction, 13*3 per cent.; extension, 

 I'l per cent. In each case the fracture took 

 place outside the welded part. The experi- 

 ments with manufactured articles were very 

 severe, but gave satisfactory results, particularly 

 in respect to the strength of the welding. 



Aluminum. The properties of aluminnm and 

 the qualities of its alloys have been compre- 

 hensively treated in an essay by Edward D. 

 Self. With those properties which promise to 

 make it so valuable in the arts, and which have 

 been described in previous volumes of the " An- 

 nual Cyclopedia," it unites a few deficiencies, 

 the most important of which is that it readily 

 unites with oxygen. Hence it is necessary, in 

 casting, to keep the metal covered with char- 

 coal or strongly-burned cryolite, to absorb 

 the oxide that may be formed and at the 

 same time protect the surface. If it absorbs 

 oxygen or becomes alloyed with silicon it is 

 made gray and brittle. The best solders for 

 aluminum are composed of tin and bismuth in 

 proportions varying according to the nature of 

 the solder that may be required. The alloys 

 of aluminum are very numerous and can be 

 usefully formed with very wide variations in 

 the proportions of the several ingredients. In 

 a general way, aluminum may be said to im- 

 prove the qualities of every metal to which it 

 is added in small quantities. It increases the 

 strength and luster of the soft metals, and ren- 

 ders others much less liable to corrosion. It 

 alloys with nearly all the useful, as well as 

 with the precious metals. The most impor- 

 tant alloys are those with copper. They form 

 a striking series, of which the alloy of 10 per 

 cent, of aluminum and 90 per cent, of copper 

 the original aluminum bronze is the most 

 prominently known. It possesses a deep- 

 golden color, has a specific gravity of T'T, can 

 be forged and shaped at a red heat, and ham- 

 mered till cold without cracking. Its tensile 

 strength has been proved at from 91,463 pounds 

 to 114,514 pounds to the square inch, with 

 elastic limit ranging from 59,815 to 85,034, 

 and elongation from -05 to 2$ per cent. In 



