30 Messrs. Carnelley and O'Shca on Melting-points and 



or 



2 12 



335 + 383 907 _ 85 



1 2 ~35 ; 



^7 +a— =— : 



1273 724 



from which 



a = 0*00460. 

 Again, 



2K + I 2 -2KI _ heat of formation of K I 

 Ag 2 + Br 2 — 2AgBr ~~ heat of formation of AgBr 

 or 



2 12 



335 383 907 85 



1 , . 2 26-1 



o + O — 



from which 



1273 ' 700 



5 = 0-00404. 



Therefore the value for Cl 2 =0*00460, 

 and for Br 2 = 0'00404; 



the inverse of their melting-points being 

 01,= ^ =0-00505, 



Br 2 =-!-r = 0-00398. 



By the use of the two former numbers for Cl 2 and Br 2 , and 

 the inverse of its melting-point for I 2 , the following table has 

 been drawn up. In the fourth column of this table, containing 

 the experimental heats of formation, (B) after a number sig- 

 nifies Berthelot, (T) Thomsen, (A) Andrews, (F & S) Favre 

 and Silbermann. In all cases the heats of formation, both 

 calculated and experimental, are for the combination of one 

 atom of halogen. 



