MECHANICS AND USEFUL ARTS. 63 



STRENGTH OF IRON. 



THE following result of an experiment on coupling cliains lately 

 made at Manchester, in England, by the London and North- Western 

 Railway Company, will be interesting to the consumers of iron : 



Best Staffordshire Iron -- first experiment diameter of chain 1^ 

 inch; stretched of inches; broke with 27 tons, 10 cwt. 



Best Staffordshire Iron second experiment diameter of chain 

 l^inch; stretched 4| inches; broke with 25 tons, cwt. 



Lowmoor Iron -- diameter of chain l inch; stretched 7 inches; 

 broke with 55 tons, 16 cwt. 



The Staffordshire Iron was made expressly for the trial, and when 

 great strength is desired, it is proper so to state, as there is a wide dif- 

 ference in the preparation of the different qualities. The New York 

 Herald contains an account of several highly interesting experiments 

 which have recently been made, with a view of testing the strength of 

 iron manufactured from the Franklinite ore of New Jersey. The fol- 

 lowing table exhibits the strength of this iron, compared with the best 

 manufactures of other countries : 



Best Swedish bar iron, Ib. 72,804 



Inferior Swedish bar iron, 53,224 



Best English bar iron, 61,660 



Inferior English bar iron, 55,000 



American manufactured from N. J. Franklinite bar iron, 77,000 



Iron manufactured of Franklinite, drawn down from a bar about one 

 inch square, and accurately gauged, required a weight equal to 77,000 

 Ibs. per square inch, to tear it asunder. This shows it to be nearly 

 fifteen per cent, better than any other iron known to commerce. 



The annexed assay on a bar of iron made from Franklinite, sent to 

 the national forges of the government of France, from the mines in 

 New Jersey, is the best evidence of its importance and immense value : 



" The bar obtained by direct treatment of the ore in the Catalan 

 forge, is 25 millimetres by 24.5 millimetres, and presents a section in 

 square millimetres of 612, in. 50. 



Kilograms. M. 



Charge under which bar began to stretch., 15,000 

 Elastic force per millimetre, - - 24 5 



Charge under which the bar broke, - 25,000 



Absolute tenacity per millimetre, - 40 8 



Elongation of the bar at the moment of fracture, 

 per millimetre, 



Aspect of the fracture, all nerves ; the bar was imperfectly welded 

 and contained fissures which diminished the real surface exposed to 

 fraction, in consequence of the absolute tenacity. Had the bar been 

 sound, it would have been greater than here appears ; at the moment 

 of fracture but little heat was disengaged." 



