Melting Points of Certain Metals. 



515 



of the results from a straight line is no greater than the prob- 

 able error of the observations. In other words, no indication of 

 a tendency of the pressure-temperature curve to bend toward 

 the pressure axis can be observed. This is confirmed by 

 inspection of the graphs reproduced in fig. 4, which were 

 obtained by plotting t or At against P for each metal. 



Fig. 4. 



lOOO 



Fig. 4. Diagram showing the relation of the change of melting point 

 A T to the pressure P (in atmospheres) for each of the four metals studied. 

 The relations between A T and P, it will be noted, are represented with great 

 exactness by straight lines. The melting point of bismuth decreases with 

 pressure while that of the other metals increases. 



It was thought that it would be of interest in this connection 

 to calculate from the Clausius-Clapeyron equation the change 

 of melting point with pressure. We may write the equation 



T 



dp 



dV 



or dt — 



T(V,- V.) dp 



42720 q 



where dt is the change in melting point for the change 

 in pressure dp, T is the absolute temperature of melting, Vi 



