Melting Points of Certain Metals. 517 



Melting Point of the Metals at Atmospheric Pressure. 



The melting points of the samples of metals used in this 

 investigation were determined with both copper-constantan 

 and Pt— Pt Rh elements which were calibrated, as stated 

 above, in steam, at the boiling points of naphthalene and ben- 

 zophenone, and at the melting point of zinc* 



Hetal 



Source 



Melting point* 



Sn 



Baker's 



231-0 



Bi 



a 



270"7 



Cd 



Kahlbaum's 



320-4 



Pb 



Baker's 



326-7 



These melting points are in very close agreement with those 

 published by the Bureau of Standards, when the difference in 

 temperature scale is taken into account. Incidentally, the 

 melting points of Kahlbaum's tin and lead were, measured. 

 The result for tin was 230*5° and for lead, 326-7°. 



Summary. 



1. There has been designed and built an apparatus suitable 

 for studying chemical and physical reactions at temperatures up 

 to 400° and under pressures up to 2000 atmospheres. Both 

 temperature and pressure in the reaction zone may be meas- 

 ured with fair accuracy. 



2. The change with pressure of the melting point of tin, 

 bismuth, lead, and cadmium has been measured ; it was found 

 to be a linear function of the pressure within the limits of 

 experimental error. 



3. By substitution in the Clausius-Clapeyron equation of the 

 data of Yicentini and Omodei on the volume change at the 

 melting point, and of Person on the latent heat of fusion, 

 dt /dp was calculated for each of the four metals. The calcu- 

 lated values show satisfactory agreement with those observed. 



4. Incidentally, the melting points of tin, bismuth, cadmium, 

 and lead were determined, and a standard curve for the cali- 

 bration of copper-constantan elements at temperature from 0° 

 to 425° is given. 



Geophysical Laboratory, 



Carnegie Institution of Washington, 



March 25, 1911. 



* The values assumed for napht. bp., benzo. bp., Zn, mp. being 217-7, 

 305-4 and 418 "2 respectively. Cf. ante p. 509, foot-note. 



Am. Jour. Sci.— Fourth Series, Vol. XXXI, No. 186.— June, 1911. 

 35 



