504 



Transactions. — Chemistry and Physics. 



The greatest discrepancies are observed in the cases of 

 bismuth and gallium, the only two metals which are known 

 to expand on freezing. 



By using the results of Heycock and Neville for the freez- 

 ing-points of alloys the value for lead becomes about 1. Their 

 experiments confirm the values of zinc, cadmium, tin, and bis- 

 muth, the first three of which give concordant results for the 

 constant. Using this value for lead, and excluding bismuth 

 and gallium, the results vary from 1 to 1-3 for twelve ele- 

 ments with melting-points ranging from —40° to -f 1,800° C. 

 The mean value is 1-16. In the table below the results are 

 compared with those of Crompton : — 



* Since the paper was communicated to t»'e Society the latent heat of 

 fusion of thallmra has been directly determ ned by the author. The 

 value thus found (mean of ten observations) gives a value of 1-02 for the 

 final expression. Thallium thus conforms to the general law. 



