PRESSURE OX RESISTAXCE OF METALS. 



623 



tion is a separate question which must be taken up later. It must first 

 of all be established that it is a true polymorphic transition in the 

 sense that the crystals pass from one crystalline system to another. 



Tellurium. I owe this to the kindness of Professor G. W. Pierce, 

 who obtained it from Mr. Samuel Wien of New York City. Beyond 

 the statement that it had been especially refined by Mr. Wien, I have 

 no direct knowledge of its purity. It was formed into wire 0.013 inch 

 diameter by hot extrusion. When the right temperature has been 

 found by trial, pieces one or two feet long may be obtained. Like 

 antimony it is excessively brittle, and must be used in the shape of a 

 grid of straight pieces. 



Tellurium is only semi-metallic in its properties, and can not be 

 soldered in the ordinary way. When fused it will stick to platinum, 

 however. Connections were made by fusing to fine platinum wire, 

 The end of the tellurium wire was allowed to rest by its own weight 

 on a piece of fine platinum, and current was passed through the plati- 

 num sufficient to melt the tellurium and flow it over the surface. 

 This connection was not entirely satisfactory, however, but appar- 

 ently cracked above 10000 kg. because of the unequal compressibility 

 of tellurium and platinum.' There was a very large permanent 

 increase of resistance after the run. 



2 4 6 8 



Pressure. Kg. /Cm.' X 10' 

 Tellurium 



Figure 22. Tellurium, resistance as a function of pressure at 0°C. This 

 curve was obtained with increasing pressure; on releasing pressure the curve 

 is not retraced, and there is a large permanent increase of resistance. 



Only one run was made on tell urium, at 0°. The points with increas- 

 ing pressure were regular, and are shown in Figure 22. The resistance 

 decreases under pressure, and the decrease is abnormally large, ini- 

 tially ten times more rapid than that of lead. 



