IRON 373 inch. The force requisite to give the har a permanent set of half a degree is about nine tenths of that which will break it. The fol- lowing table shows the effect of successive remeltings on the strength of cast iron, from determinations by Fairbairn; the iron used was Eglinton No. 3, hot blast : NO. OF MELTINGS. Sp. gravity. Mean breakingw'ght In Ibs. per aq. In. for bars 4 ft. 6 In. be- tween supports. Resistance to compression for cubei 1 in. square. 1. . 6-969 LtM. 490-0 Tons. 44-0 2. 6'970 441*9 48*6 8 6*886 401-6 41-1 4. 6'988 413-4 40-7 5 6-842 481-6 41-1 6. . 6-771 483-7 41*1 7.... 6-879 449-1 40'9 8 7-025 491*8 41 '1 9.... 7-102 646-5 55-1 10 7-108 666-9 57'7 11. 7-113 651-9 12 7-160 692-1 18.. 7-184 684*8 TS'l 14 7-580 603*4 66*0 15 7-248 871-1 95 '9 16. 7-830 851*8 76' 7 17 lost. 70 "5 18... 7-385 812*7 88-0 Melting per e cannot have any effect on the physical properties of iron, and any change consequent on melting must be referred to change in chemical composition, leaving out of consideration accidental imperfections of cast- ing. Melting may be effected in three ways : in a crucible, in a cupola or shaft furnace, or in a reverberatory or air furnace. In a cruci- ble, by exclusion of air, the iron should be un- changed ; in a cupola the atmosphere is redu- cing, and an increase of carbon or silicon may result; while in the oxidizing atmosphere of an air furnace the silicon and carbon are gradu- ally removed. The following tables give the strength of wrought iron of various manufac- ture, composition, &c., under varying strains; steel is added for comparison : Tensile Strengfft of Iron Bars. (Eirtcaldy.) KINDS. Breaking weight per i j. in. in pounds. Difference between ori- ginal and fractured area, pr cL Ordinal area. Fractured area. Swedish (charcoal) 47,584 58,036 65,166 69,570 69,726 66,868 69,272 56,447 160,520 150,984 140,920 125,180 102,118 97,721 82,818 68,838 70-5 61 '6 68-7 52-4 41-5 32-1 28'4 10-2 Staffordshire " Yorkshire " Lowmoor "... Staffordshire B. B. scrap... Scotch extra best best " best beat .... " common . . . Eusslan C. C. N. D Tensile Strength of Iron Plates. (KirTcaldy) Breaking w'ght ? Breaking w'gbt -if , per aq. inch, ill per sq. inch, -H KINDS. lengthwise. H crosswise. sis Orl-". Fract'd Orig. Fract'd |-3 t area. area. 5-5,5 ana. area. all Yorkshire 68,686 92,468 86*6 56,546 70,919 20-8 Staffordshire,Brad- 60,697 65,176 70,968 68,180 15-7 12*7 51,025 48,000 55,490 51,291 8-0 6-4 Scotch best boiler. Staffordshire best best 48858 53781 9*1 Scotch ship. " common. . . 47,780 43,881 80.085 46,489 4*6 6*6 44,866; 45,521 42,788] 43,460 2*5 1-6 Average Results obtained oy K of puddled Steel and Ironj den; temperature GO" F. (t and Steel") icure of 64 square Ban om Surahammar, Swe- "" Knut St life's "Iron Hard puddled steel Middling hard puddled steel Soft puddled steel Puddled iron . . . Breaking weight Elonga- 1 P* r * in- on the tion by original rupt're. 6-20 6-93 10-48 20-86 Lb!. 70,272 48,819 89-81 85-89 81-81 21-55 Breaking weight per iq. in. on the section of rupture. 122,240 116,670 112,698 120,770 The elongation given in this table is very low, owing to the fact that the experimenter, Herr Thal6n, did not measure the elongation in that foot of length in which the fracture took place, but in the other 4 ft. of the length of the bar. Results of Experiments on tlus Tensile Strength of Sessemer Steel and Cast Steel at 60' (From Knut Strife's "Iron and Steel.") F. KINDS. Amount of carbon per cent. Amount of phos- phorus per cent. BREAKING W'GHT. Elonga- tion by rupture. Load per sq. In. at the limit of elaitlcity, Ibs. Original area, Ibs. Fractnred area, Ibs. Tilted Bessemer steel from Hogbo 1-10 0*84 1*16 0*61 0-018 0-028 0-011 0-080 127.564 64,708 189,847 82,549 216,153 141,219 159,610 172,804 2-9 16-7 4-6 6-5 85,481 84,990 71,707 56,925 Rolled Bessemer steel from Carlsdal Rolled cast steel from Wikmanshyttan (Uchatius steel). . . Tilted cast steel from Krupp Results of Experiments on the Tensile Strength of Iron at 60 F". (From Knut Styfffs "-Iron and Steel.") Amount of Amount of BEEAKlNr, 8QUAR VEIGHT PER S INCH. Elongation Load per sq. cant. per cent. On original area, Ibs. On fractured area, Ibs. by rupture per cent. limit of elasticity, Iba. Rolled puddled iron from Lowmoor (1-21 0*068 58,944 0-07 0*295 72531
- from Dudley
0-09 0*346 47 553 6 032 7*4 28,683 " " from Motala works, Sweden .. Rolled Iron made In charcoal hearth, Sweden ' In Lancashire hearth, Sweden 0-20 0-18 0-07 0*020 0*264 0-022 62^681 63,473 45,014 100,61*5 76,864 192,768 17-8 8- 3 22-0 29,506 40.4S5 24,860
