Resistance of Metals and Alloys, 

 Commercial Aluminium, 97*5 per cent., fine. 



289 



B*. 



1-0352 

 09134 

 0-7887 

 0-6869 

 0-6064 

 06021 

 0-5671 

 0-4577 

 0-3672 

 0-3127 

 0-1070 



0-3744 

 0-2402 



t°. 



pt. 



193-3 

 144-4 

 91-45 

 50-1 



18-85 



15-65 



10 



4898-1 

 4321-8 

 3731-8 

 3250-1 

 2869-2 

 2S48-9 

 2683-2 

 2165-6 

 1737-6 

 1479-5 

 506-3 



506-3 

 324-8 



1* 



190-4 

 143-0 

 91-6 

 50-7 

 19-25 

 15-95 

 10 



■ 44-3 



■ 81-9 

 •106-1 

 ■197-1 



■ 197 

 ■219 



w 



Remarks. 



In liquid ethylene. 

 In liquid oxygen. 



This ratio was obtained from 

 a longer coil of the same 

 wire immersed in oxygen 

 boiling under reduced 

 pressure. 



Volume- specific resistance at 0° C. . =2665 C.G.S. units. 

 Mean temperature-coefficient between 



0° C. and 100° C =-00435. 



Contrary to usual experience, this Commercial Aluminium 

 has a larger temperature-coefficient between 0° C. and 100° C. 

 than the purer metal, and larger even than that of the pure 

 copper. 



§13. 



VII. Iron. 





It is needless to say that we had great difficulty in obtaining 

 any sample of iron which could properly be called pure. 

 We have not yet succeeded in obtaining iron wire drawn 

 directly from pure electrolytic iron. Colonel Dyer, of the 

 Elswick Ordnance Works, kindly sent us samples of iron very 

 free from carbon, silicon, and phosphorus but in which unfor- 

 tunately manganese was still present to the extent of nearly 

 0*25 per cent, and sulphur § 01 per cent. From Messrs. 

 Hopkins and Williams we procured samples of iron, pre- 

 pared especially for them, and of a high degree of purity 

 and very soft and well annealed. The electrical behaviour 

 of this last sample shows it to be almost free from admixture 

 of other elements. We call the first iron from Armstrong's 

 works, Iron A, and the other Iron H. W. The last iron has 

 by far the higher conductivity. The Iron A proved to be 

 sufficiently soft to work cold under the hammer and was drawn 

 without heating into a very uniform wire. 



