336 Effect of Liquid Air Temperatures on Iron and its Alloys. 



cent. Here the ductility is extraordinary at not only normal but low 

 temperatures, probably the highest known for any iron alloy, and 

 certainly for an alloy having such tenacity as 85 tons per square inch. 

 There is still present in this alloy 68 per cent, of iron, yet the tendency 

 of the latter metal to become brittle is not only entirely checked at the 

 low temperature ; but the elongation, already so great, is considerably 

 increased, viz., from 60 to 67 \ per cent. There is also an increase of 

 tenacity in both cases, viz., a rise from 10 to 38 per cent. Thus the 

 nickel present causes the bar under high tension, and at - 182 C., to 

 remain far more ductile than the very best ductile iron of one third the 

 tenacity. Although the action of nickel has been specially referred to, 

 it must not be overlooked that in this alloy there is also present 6 per 

 cent, of manganese, which in its ordinary combination with iron, that 

 is with no nickel present, would confer intense brittleness upon the 

 iron and render it more brittle than if not present. This treble 

 combination of nickel, manganese, and iron, appears to reverse all the 

 known laws of iron alloys. 



We have to thank the mechanician of the Davy-Faraday Laboratory, 

 Mr. C. N. Cooke, for able assistance in the conduct of the experiments. 



