332 Sir J. Dewar and Mr. E. A. Hadfield. E/ect of [Nov. 24, 



liquid air, in other words, a steel having high tenacity at normal tem- 

 perature is practically unaffected by liquid air. 



Tests were carried out in 



Iron, Nickel, and Silicon 

 Iron, Manganese, and Chromium 

 Iron, Manganese, and Silicon 

 Iron, Chromium, and Aluminium 

 Iron, Chromium, Silicon 

 Iron, Chromium, Copper 

 Iron, Chromium, and Tungsten 



liquid air on specimens repre- 

 senting these alloys, but the 

 results do not call for any 

 special comment, in all cases 

 the specimens behaving in the 

 normal manner, i.e., showing 

 increase in tenacity and de- 



. crease in ductility in liquid air. 



Iron, Manganese, Copper. Test No. 19 (C 0'25, Mn 2-01, Cu 1-39 

 per cent.) shows a remarkable rise in tenacity, the elongation remaining 

 unaffected by the low temperature. It is remarkable that the copper, 

 which is present only to the extent of 1 J per cent., absolutely neutralises 

 what would be the action of manganese, which clearly produces brittle- 

 ness and hardness at low temperatures. 



r Tests were carried out on 



Iron, Cobalt, Manganese, Silicon | specimens representing these 



Iron, Chromium, Manganese, Silicon -{ alloys, but the* results do 

 Iron Nickel, Manganese, Aluminium I not call for any special com- 



L ment. 



Iron, Nickel, and Manganese. In this class a number of specially 

 interesting results were obtained. There is an important alloy, 

 No. 1109D (C 0-60, Mn 5'04, Ni H'55 per cent.), including two 

 elements, which, if added separately in the same proportions to 

 iron, would cause extreme brittlenes^. Most singular to say, this 

 double combination now confers extraordinary toughness. This alloy 

 is probably the most ductile form of iron alloy known, in several cases 

 an elongation of no less than 75 per cent, having been obtained at 

 normal temperature. Taking the first specimen, No. 60, under liquid 

 air treatment, this material drops in elongation from 70 25 per cent., 

 this remaining ductility even now being very great. This is the first 

 specimen met with in which the ductility remains comparatively high. 

 A further test carried out on the same steel shows a similar result. It 

 may be mentioned that the magnetic qualities of the specimen remained 

 unchanged at - 182 C. 1109D may be termed almost non-magnetic, 

 though not so much so as manganese steel. 1109D is much more 

 sensitive to magnetic changes by temperature, though to an ordinary 

 magnetic test it appears inert. 



The next specimen, No. 61 (C 1-00, Mn 6-05, Ni 17-91 per cent,), 

 shows a further increase in nickel percentage, and this is clearly the 

 factor in preventing loss of ductility at - 182 C., the ductility only 

 decreasing from 5742 per cent. Another specimen taken, No. 114 



