108 Mr. C. T. Blanshard on the Bole of Atomic Heat 



2. The variation is greatest with elements of low atomic 

 weights, becoming less and less as the atomic weight increases. 



~ 7 O Ft 



I hope in the next place to show in a tabular form that the 

 melting-points of the elements are intimately connected with 

 their atomic heats, and that four general laws govern this con- 

 nexion. Were sufficient data to hand with regard to latent 

 heat of fusion &c, there is no doubt that many similar relation- 

 ships would be established. There is evidently plenty of work 

 before physical chemists in this direction. In the arrange- 

 ment of the groups of elements I follow a plan u«ed by Lothar 

 Meyer, of using Roman numerals combined with lettering. 

 Thus the Li group is L, the Cu is I. a.; Group II. is Ca &c. ; 

 II. a Be &c; II. b Fe, Ru, Os. In placing the iron elements 

 here, and not in a separate group, I am following W. Preyer, 

 Das genetische System der chemisclien Elemente, Berlin, 1893. 

 The groups are entirely arranged by their atomic heats, but 

 will be found to be practically identical with Lothar Meyer's 

 classification. The melting-points taken are the most correct 

 up to date, from (1) the late T. Carnelley's ' Physico-Chemical 

 Constants/ 1887 ; (2) H. Landolt and R. Bornstein, Phys.- 

 Chemische Tabellen, Berlin, 1891 ; (3) The Chemical Society's 

 Journal. Several determinations are very rough, others are 

 altogether wanting. The specific heats, which are much more 

 complete, are from the last two sources and ' Watts' Dictionary 

 of Chemistry.' Thev are all taken at as near as possible the 



J J r 



constant t°, 15°. The atomic weights are from Landolt and 

 Bornstein and the Chemical Society's Journal. From these 

 and the specific heats I have calculated the atomic heats with 

 much greater accuracy than has hitherto been thought 

 necessary. Blanks denote that no reliable data are to hand. 

 A query denotes that the observation has been made, but not 

 accurately. 



Group. 



Element. 



Melting-Point. 



Atomic Heat. 



I 



Lithium. 

 Sodium. 



180 

 95-6 



6-608 

 6-526 







Potassium. 



62-5 



6303 





Rubidium. 



38-5 







Caesium. 



26-5 





La 



Copper. 



1054 



5-870 





Silver. 



1040 



5-936 





Gold. 



1035 



6-383 



II. 



* Calcium. 

 Strontium. 



... 



7-216 





Barium. 



1100? 





* Bun sen's value for Ca seems too high ; the atomic heat of this element 

 will probably prove to be less than that of K. 



