368 Dr. T. Carnelley on the 



the variation of specific gravity and the electric properties of 

 steel, the T. E. H., specific resistance, and magnetic moment 

 are in some very intimate way connected with the volume of 

 a unit of mass. This would imply a connexion of these phe- 

 nomena with the intermolecular spaces of steel. 



In conclusion, it gives me great pleasure to acknowledge 

 my indebtedness to Prof. Kohlrausch for much kind assist- 

 ance throughout the course of the experiments. 



Pkys. Inst. Univ. Wiirzburg, 

 February 1879. 



Xlil. Influence of Atomic Weight. By Thomas Carnelley, 

 D.Sc, Assistant Lecturer on Chemistry in the Owens Col- 

 lege. 



[Continued from p. 324.] 



Influence of Atomic Weight on the Physical Properties of 

 Compounds. 



SO far, we have endeavoured to show the influence of atomic 

 weight on the properties of the elements ; we shall now 

 continue this subject with regard to the influence of atomic 

 weight on the physical properties of compounds. 



MendeljefFs Law of Periodicity runs thus : — " The proper- 

 ties of the elements are a periodic function of their atomic 

 weights.'''' This law may be supplemented as follows : — " The 

 properties of the compounds of the elements are a periodic 

 function of the atomic weights of their constituent elements." 

 In a paper recently (June 19, 1879) read before the Royal 

 Society the author has shown that this holds good as regards 

 the melting- and boiling-points and heats of formation of the 

 normal halogen compounds of the elements and of certain 

 compounds of the elements with monatomic alcohol radicals ; 

 and for the present we shall limit ourselves to these. 



A. Melting- and Boiling-points and Heats of Formation. 



I. Normal Cldorides, Bromides, and Iodides of the Ele- 

 ments. — In whatever way the melting-points, boiling-points, 

 and heats of formation of these compounds be arranged, 

 provided only they are arranged systematically, we always 

 find that certain definite and regular relations may be traced 

 between the numerical values for the above-mentioned physical 

 properties and the atomic weights of the compounds. Some 

 of the more important conclusions arrived at areas follows : — 



(1) The melting- and boiling-points and heats of formation of 



