ELECTRICAL RESISTANCE UNDER PRESSURE. 



107 



of solid gallium was sculptured out with considerable difficulty with 

 a warm wure as a sculptor's tool, four platinum terminals were set 

 into it, and measurements made of the pressure coefficient of resist- 

 ance by the potentiometer method. The temperature coefficient 

 of the solid at atmospheric pressure was also determined with this 

 free specimen. This seems to be the first time that this has been done. 

 Previous measurements of the temperature coefficient of the solid 

 have been on the solid in glass, and no correction has been applied 

 for the constraining effect of the glass. After the completion of the 

 resistance measurements on the free solid another point was found 

 on the melting curve, which checked with the points found previ- 

 ously. The resistance of the solid showed no discontinuities within 

 the errors of the measurements, and hence it is not likely that there 

 are new modifications in the region of the measurements. This was 

 rather a disappointment. 



TABLE XI. 



Gallittm. 



Melting Curve. 



The smoothed coordinates of the melting curve are given in Table 

 XI, and the observed points with the curve are shown in Figure 8. 

 For the melting point at atmospheric pressure I used the value 

 determined for this sample by Mr. Boyer, which is 29.85°. This is 

 lower than the value originally given by deBoisbaudran,^* 30.15°, 



