﻿Fields on the Electric Conductivity of Bismuth, 493 



diameter, which was pushed over them and soldered to both, 

 thus forming a closed cylindrical vessel with the pole-pieces 

 as ends. A slit made at the top for about one quarter of the 

 circumference served to admit the small spiral or the ballistic 

 coil, and two extra holes in it with brass tubes fitted in them 

 served as inlet and outlet for a flow of water. In this way 

 it was possible to have a constant flow of water over the poles 

 and spiral. 



The temperature of the spiral was measured by means of a 

 thermoelectric junction placed beside it inside the copper 

 case ; and the same galvanometer was used to measure the 

 temperature and field, it being never required for both 

 purposes simultaneously. 



Experiments were first of all made with the large spiral, 

 using either ice or water of the temperature of the air in the 

 bath, and the two series given below in Table I. for 0° and 

 18° C. are chosen from a number done in this way. 



Table I. 



o°c. 



18° C. 



Magnetic 

 Field. 



Resistance. 

 Ohms. 



Percentage- 

 Increase of 



Magnetic 

 Field. 



Resistance. 

 Ohms. 



Percentage- 

 Increase of 



C.G.S. 



Resistance. 

 0-0 



C.G.S. 



Resistance. 







2243 







240 







970 



22-8 



1-7 



770 



24-23 



0-8 



1220 



2302 



2-7 



960 



24-38 



1-5 



1700 



2349 



4-7 



1740 



24-85 



3-4 



2800 



24-85 



10-8 



1 2860 



25-96 



8-2 



4120 



26-74 



19-2 



4160 



27-55 



14-8 



7110 



31-41 



400 



7190 



31-36 



30-7 



6340 



30-13 



34-4 



6260 



30-22 



25-9 



6830 



30-81 



37-4 



6880 



30-95 



290 



7350 



3167 



41-3 



7270 



31-56 



31-5 



7970 



32-55 



451 



7930 



32-40 



35-0 



8700 



33-79 



50-7 



8740 



33-53 



39-7 



9690 



35-33 



57-5 



9650 



34-85 



45-2 



10910 



37-37 



66-7 



10950 



36-72 



53-0 



13070 



4043 



80-3 



12750 



3895 



62-3 





Series a 



; 0° and 18° 



O. with larg 



e spiral. 





In all the experiments with this spiral the constancy of 

 the temperature was tested by taking the resistance of the 

 spiral when raised clear of the poles each time the field was 

 measured ; and the temperature could be got very exactly 

 from the tempera ture-coefncient curve. Throughout a series 

 the temperature never varied more than one degree, and for 

 the greater part of the series it was constant PI. XV. fig. 5 



