314 



BRIDGMAN. 



ical details were very different. The values of e.m.f. are shown in 

 Table XV and Figure 16; the Peltier heat and the Thomson heat are 

 not given in detail. The effect is, as before, initially negative, the 

 curves of e.m.f. at constant temperature passing through a very flat 



'0° 10° 20 



' 30° 40° 50° 



Temperature 

 Commercial Aluminum 



60° 70° 80" 



FiGUEE 16. Commercial Aluminum. Thermal E.M.F. of a couple com- 

 posed of one branch of uncompressed metal, the other compressed to the 

 pressure in kg. /cm.- indicated on the curves, the junctions being at 0°C and 

 the temperature plotted as abscissae. 



minimum and then rising. The pressure and the absolute value of 

 the minimum both decrease rapidly at higher temperatures. The 

 curves are throughout concave upwards. But at 25° the numerical 

 value at the minimum is only —0.03 X 10"^ against —0.1 X 10"^ for 



