Steel in its hardest state being too brittle for most purposes, the requisite strength and elasticity are obtained by tempering or letting down the temper, as it is termed-which is performed by heating the hardened steel to a certain degree and cooling it quickly. The requisite heat is usually ascertained by the color which the surface of the steel assumes from the film of oxide thus formed. The degrees of heat to which these several colors correspond are as follows: At 430°, a very faint At 450°, a pale straw color Suitable for hard instruments; as hammer-faces, drills, &c. At 470°, a full yellow.......... ( For instruments requiring hard edges without elasticAt 490°, a brown color..... ity; as shears, scissors, turning tools, &c. At 510°, brown, with purple spots.... At 538°, purple... At 550°, dark blue At 560o, full blue.............. (For tools for cutting wood and soft metals; such as plane-irons, knives, &c. For tools requiring strong edges without extreme hardness; as cold-chisels, axes, cutlery, &c. At 600°, grayish-blue, verg- For spring-temper, which will bend before breaking; ing on black... as saws, sword-blades, &c. If the steel is heated higher than this, the effect of the hardening process is destroyed. ROGERS & CO. DEALERS IN Wrought Iron Beams, GIRDERS, T and Angle Iron, MERCHANT'S BAR IRON. Scotch Pig, Lake Superior Charcoal, Missouri Charcoal, and Bituminous Pig Iron. Lump Lehigh Coal, (FOR FOUNDRY USE.) Blossburg Coal, (FOR BLACKSMITH'S USE.) Lackawanna Coal, Nut, Range, Small Egg and Large Egg, FIRE BRICK AND FIRE CLAY COAL FACING. 144 Market Street, CHICAGO, ILL. Weights of Weight of Running Foot in Pounds. (channel) and iron may be found from the Table of Angle and T iron in the following manner, provided the web and flanges are of the samə mean thickness: Let the number of the side column referred to equal half the sum of the depth of web and breadth of both flanges; then twice the weight corresponding thereto will be the weight per lineal foot, according to the thickness, of the channel or iron required. Particular attention paid to the Shipment of Cars, and Materials for Cars, to all parts of the world. ... 9.57 ... 10.83 12.07 13.28... 14.47 15.62 ... 17.86... 20. 9.75 11.04 12.3 13.54 ... 14.75 15.93 18.23 20.42 9.93 11.25 12.54 13.8 15.04... 16.25 18.59 20.83 11.46... 12.77 ... 14.05 15.33 ... 16.56 ... 18.96 ... 21.25 736 8.75 10.12 7.49 ... 8.91 10.3 7.62 11.67 ... 13.01 ... 14.32 ... 15.61 ... 16.87 ... 19.32 ... 21.67 9.06... 10.48 ... 11.87 ... 13.24 ... 14.58 ... 15.9 17.19 ... 19.69... 22.08 9.22 ... 10.66 ... 12.08 ... 13.48 ... 14.84 ... 16.18 ... 17.5 ... 2.05 ... 22 5 7.88 9.37 10.85 ... 12.29 ... 13.71 ... 15.1 ... 16.47 17.81 20.42 ... 22.92 8.01 9.53 11.03 12.5 13.94 15.36... 16.76... 18.12 20.78 8.14 9.69 11.21 12.71 14.18 15.62... 17.04... 18.44... 21.15 23.73 8.27 9.84 11.39 12.92 14.41 ... 15.88 17.33 ... 18.75.. 21.51 ... 24.16 8.40 ... 10. ... 11.57 ... 13.12 ... 14.65 ... 16.15 ... 17.62 ... 19.06 ... 21.87 ... 24.58 8.3... 10.16 ... 11.76 ... 12.33 ... 14.88 ... 16.41 ... 17.9 19.37 ... 22.24 ... 25. 8.66... 10.31 ... 11.94 ... 13.54 ... 15.12... 16.67 ... 18.19 ... 19.69 8.79 10.47 12.12... 13.75 15.35 ... 16.93 18.47 20. 22.97 25.83 18.76 ... 20.31 23.33 26.25 19.05 16.29 ... 17.97 19.62 ... 20.62 23.7 26.66 21.25 ... 24.42 ... 27.50 16.76... 18.49 ... 20.19 ... 21.87 ... 25.15 ... 28.33 ... 18.16 ... 20.05 ... ... 23.63 ... 25.62 ... 29.53 ... 33.33 26.25 ... 30.26 ... 34.17 11.65 13.91 16.13 ... 18.33 20.51... 22.66... 24.78 26.87 30.99 35. 3/4 11.91 18.75 20.98 ... 23.18 25.35 27.5 31.72 35.83 12 12.17... 14.53 16.86 19:17 21.44 23.7 25.92 28.12 32.45 36. 7 14.84 17.23 ....19.58 21.91 ... 24.22 26.5 28.75 ... 33.17 ... 37.5 15.16 ... 17.59 ... 20. 22.38 24.74 ... 27.07 ... 29.37 ... 33.9 ... 38.33 17.96... 20.42 22.85 ... 25.26 ... 27.64... 30. 34.63 39.16 23.32 25.78... 28.22 30.62... 35.36 ... 40. 23.79... 26.3 28.79 31.25 36.09 40.83 24.26 26.82 ... 29.36 31.87 36.82 41.67 24.73 27.34 29.93 32.5 |