74 Profs. J. Dewar and J. A. Fleming. On the Electrical 



there is no tendency of the resistivity carve to a minimum value. 

 Down to the lowest temperatures reached in these experiments, the 

 resistivity of bismuth continues to decrease in a perfectly regular 

 manner, and in such a way as to show that it would be no exception, 

 in all probability, to the ordinary law, that resistivity of pure metals 

 vanishes at the absolute zero of temperature. On comparing the 

 results of these measurements with those in the former experiments 

 made with chemically prepared bismuth, it is seen that the electro- 

 lytic bismuth used by us has a very much lower resistivity at C., 

 viz., 108,000 units, and it has a lower value than that given by 

 Matthiessen for pure bismuth, which is 129,700. We have, then, an 

 additional indication that the bismuth used by us in the experiments 

 in 1895 must have contained sufficient, though slight, impurity to 

 markedly alter its resistivity, and to change entirely the character of 

 the resistivity curve. With this- electrolytic bismuth we have repeated 

 the experiments which we made last year, on the variation of the 

 electrical resistance of bismuth when placed transversely to the 

 direction of the force in a magnetic field, and when cooled to the 

 temperature of liquid air. For this purpose we constructed a flat 

 spiral of the electrolytic bismuth, so arranged that its resistances 

 could be measured at ordinary temperatures, and at the temperature 

 of liquid air, by immersing it in a flat vacuum- jacketed test-tube, 

 both when in a powerful magnetic field, and when merely in the 

 terrestrial field. With this electrolytic bismuth we have confirmed the 

 observation which we made last year, with a small sample of electro- 

 lytic bismuth, viz., that the effect of a given transverse magnetic 

 field in increasing the resistivity of bismuth is immensely increased 

 by cooling the bismuth to the tempera.ture of liquid air. The figures 

 in the following table will show the actual results obtained in these 

 last experiments : 



Variation of Electrical Resistance of Electrolytic Bismuth in 

 Magnetic Fields of different Strengths. 



