PRESSURE ON RESISTANCE OF METALS. 621 



>\' 



Antimony. This was obtained from Eimer and Amend. Thev 

 were so kind as to make a special analysis for me; this showed SI) 

 99.45%, As trace, Fe trace, other foreign metals none. It was 

 formed into wire 0.013 inch diameter by hot extrusion. It is neces- 

 sary to heat to 350° or 400° C, and apply a pressure of 10000 or 15000 

 kg. A little trick is necessary to successfully extrude it ; this matter 

 is described at length in a forthcoming number of The Ph;\'sical 

 Review. The wire is excessively brittle. It cannot be wound into 

 any sort of a spiral, but must be used in straight lengths, in a sort of 

 grid. The grid used was composed of two pieces laid together in the 

 form of a V in grooves cut on a bone cylinder, attached together by 

 soldering with "fine" solder at the bottom of the V. Connections 

 to the leads was made by soft soldering at the top to flexible copper 

 conductors made of many strands of wire 0.002 inch diameter. The 

 soldering must be performed by a rapid touch, because the fine wirp 

 alloys very rapidly to form an alloy of much lower melting point than 

 the solder applied. The initial resistance at 0° was 0.90 ohms. The 

 sensitiveness is not as great as would have been desirable, but the 

 difficulties of manipulation in making a larger grid would have been 

 very great. 



Six runs were successfully made, at 0°, 25°, 50°, 75°, 100°, and at 0° 

 again. It was a great gratification that such high pressures could be 

 applied without rupturing this excessively brittle substance. x\t 

 the low temperatures pressure was transmitted by petroleum ether, 

 and at higher temperatures by kerosene. The behavior of antimony 

 is abnormal, like that of bismuth, since it has a large positive pressure 

 coefficient. There is rather large hysteresis, but within the limits of 

 error the mean of points with increasing and decreasing pressure are 

 linear. At 0° there was a permanent increase of resistance of 5% 

 of the total resistance after the first application of pressure. After 

 the first application of pressure the permanent changes of resistance 

 remained much smaller. 



The smoothed results are shown in Table XIX, and the experimental 

 values of the mean coefficient in Figure 21. The change of pressure 

 coefficient with temperature is abnormally large. 



The temperature coefficient of this antimony wire between 0° and 

 100° was 0.00473. This may be compared with the value 0.00418 

 for cast antimony given by Matthiesen and von Bose.^^ Doubtless 

 part of the difference at least can be ascribed to difference of mechani- 

 cal treatment. 



18 A. Matthiesen und M. von Bose, Pogg. Ann. 115, 353-39ti (1862). 



