ii9i 



trom llie abovo talile il is seen tliat in these pro|)erties also tlierö 

 are distinct indications of iierioiiicity. Tiie transitional elements 

 Fe and Ni liave |)racticall_y eqnal values l'or these properties. 



As the atomic weight of elements in the same periodic group 

 increases the valne for YouN(i's modulus and torsional rigidity decreases. 

 In the sni) group />' of the lirst grouj) of periodic classification (Cu, 

 Ag, An), gold having the highest atomic weight has the smallest 

 values for Yolng's modulus and torsional rigidity. Similar are the 

 behaviours of zinc, cadmium, tin and lead. 



Sufiicient data are available in the case of the temperature coelïicient 

 of torsional rigidity and hence distinct periodic curves are obtained ; 

 the alkali metals, Li, K, Na, Rb and Cs lie on the topmost points 

 whilst copper, silver and gold lie on a straight line on the minima. 



Fig. 3. 



Specific heat. During recent years the determination of specific 

 heats of substances at low temperatures was attracting the attention 

 of numerous investigators. 



Richards and Jackson (Zeit. Phys. Cliem, J 910. 70, 414) have 

 carefully determined the specific heats of various elements between 

 — 188° and -|- 2*^°- F'Oin Iheir experimental data, they come to 

 the conclusion that the atomic heats of various elements between 

 the above range of temperature conform approximately to Dui.ong 

 and Pktit's law, the value of the constant being 5.3. There are 



26* 



