292 



Profs. Dewar and Fleming on 



the Electrical 



R* 



t°. 



pi. 



Pt 



1-8475 



195-3 29730 



192-3 



1-4448 



133-7 23250 



132-7 



1-2067 



9035 19419 



90-55 



1-0058 



51-7 16185 



52-3 



0-8484 



18-7 14653 



1910 



0-7707 



1-30 



12402 



1-35 



0-5876 





9456 



- 43-6 



0-4500 





7242 



- 81-9 



0-1185 





1908 



-197-1 



Volume-specific resistance at 0° C. . = 12323 

 Mean temperature-coefficient between 



0° C. and 100° C = '00622 



§15. IX. Tin. 



This metal is one of the easiest to obtain in a state of 

 purity. Very pure grain tin was melted in a porcelain 

 crucible under paraffin and then pressed warm in a steel 

 press with a hard steel plunger. The pressure was applied 

 by the hydraulic testing-machine in the University College 

 Engineering Laboratory, a pressure of 25 tons on the square 

 inch Was sufficient to press out a very uniform wire of pure 

 tin. The measurements were as follows : — 



Length = 300 centim. Mean diameter = 0*067505 centim. 



Mean sectional area = 0*0035790 sq. centim. 

 T rlO 9 section - ] 

 length J 



rl 



4-0766454 = log 10 R. 



R*. 



t°. 



pt. 



pt. 



Remarks. 



1-9809 



176 



23632 



173-6 





1-8233 



146-1 



21752 



144-7 





1-5340 



91-45 



18301 



91-6 





1-3398 



52-10 



15984 



52-70 





1-1849 



18-75 



14136 



1915 





1-1512 



12-70 



13734 



13-0 





1-0981 



1-0 



13100 



10 





0-8941 





10667 



- 44-2 





07366 





8788 



- 81-9 



In C0 2 and ether. 



0-2849 





3399 



-197-1 



In liquid oxygen. 



Volume-specific resistance at 0° C. . . = 13048 

 Mean temperature-coefficient between 



0°Candl00°C ='00440 



§16. X. Magnesium. 



This wire was prepared for us by Mr. George Matthey 

 and was free from any admixture of zinc. As the wire was 



. 



