THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



JUL Y 1884. 



I. The Periodic Law, as illustrated by certain Physical Pro* 

 perties of Lnorganic Compounds. By Thomas Carnelley, 

 D.Sc, Professor of Chemistry in University College, 

 Dundee*. 



[Plate I.] 



THE object of the present paper is : — (1) To illustrate the 

 truth of the Periodic Law by means of the melting- 

 and boiling-points and heats of formation of the halogen com- 

 pounds of the elements. (2) To apply the facts thus obtained 

 to the calculation of unknown melting- and boiling-points. 

 (3) To show how a knowledge of the melting- and boiling- 

 points of the compounds of an element may be used for the 

 determination of its atomic weight, when the application of 

 the methods of specific heat and vapour-density do not give 

 satisfactory results, (4) To show how the position of an 

 element in the general classification may be inferred from 

 the known melting- and boiling-points of its compounds. 



It is only within the last few years that the number of 

 melting- and boiling-points determined for inorganic com- 

 pounds has rendered it possible to draw any conclusions as to 

 the laws which govern theni. This has been chiefly due to 

 the difficulty of determining the melting- and boiling-points 

 of bodies which fuse or boil only at temperatures which are 

 beyond the range of an ordinary thermometer. This difficulty 



* Communicated by the Author. 

 Phil. May. S. 5. Vol. 18. No. 110. July 1884. B 



