On the Electrical Resistivity of Electrolytic Niclcel. 



53 



18° C. The mean diameter calculated from the length and density i^ 

 then "009 97 inch. Hence we have — 



Mean diameter from micrometer measurement 0-00985 inch. 



Mean diameter hy specific gravity and length measure- 

 ment 0-00997 „ 



The mean of both means is 0*00991 inch = 0'Q2567 cm. This last 

 number was taken as the value of the mean diameter. 



The nickel wire was then soldered to thick copper leading-in wires, 

 and wound on a frame of a kind suitable for immersion in liquid air. 



A description of this particular kind of resistance coil, which has 

 proved itself to be exceedingly suitable for low temperature work, was 

 given in a paper describing the result of numerous observations on the 

 resistivity of metals at low temperatures, published by Professor Dewar 

 and the present author in 1893.* 



A coil having been thus constructed, its resistance was taken at 

 various temperatures in a bath of paraffin oil, and the results are as 

 shown in the table below. The temperature of the bath was measured 



Observations on the Resistance of Electrolytic Nickel Wire. 





Total 



Platinum 



Centigrade 



Volume 



Obs. 



resistance of 



temperature, 



temperature, 



resistivity in 





nickel -n-ire. 



pt. 



C. 



C.G-.S. units. 



1 



3-4284 



1-057 



1 -232 



6974 



2 



3-7563 



18 -489 



18-29 



7641 



3 



3 -9470 



28 -676 



28 -32 



8029 



4 



4 -1109 



36-959 



36 -51 



8363 



5 



4 -3506 



48 -740 



48-21 



8850 



6 



4 -5679 



58 -773 



58-23 



9292 1 



7 



4-5778 



59 -315 



58-78 



9312 1 



8 



4 -7493 



67 -384 



66-85 



9661 ; 



9 



5-0403 



80 -550 



80-11 



10253 ■ 



10 



■ 5 -2018 



88-587 



88-25 



10582 



11 



5-3000 



93 -544 



93 '29 



10782 



12 



5 -3882 



95 -731 



94-88 



10961 



13 



5 -2379 



89 -289 



88-97 



10655 



14 



5 -0094 



78 -482 



78 -02 



10190 



15 



4 -7273 



66-700 



66-17 



9616 



16 



4 -5260 



57 -151 



56-61 



9207 



17 



4 -3586 



■ 48-704 



48-18 



8865 



18 



4-1323 



37 -906 



37-44 



8406 



19 



3 -9620 



31 -226 



30-83 



8060 



20 



3-8112 



21 -550 



21 -30 



7753 



21 



3 -4318 



2-205 



2-35 



6981 



22 



2-090 



-80-72 



-78-2 



4251 



23 



0-710 



-196-89 



-182-5 



1444 



* See 'Phil. Mag.,' September 1893, p. 279, "On the Eesistance of MetaU and 

 AUoy3 at Temperatures approaching tbe Absolute Zero." 



