498 Prof. T. Carnelley on the Periodic Law. 



I have made a careful comparison of the physical properties 

 (chiefly melting- and boiling-points) of a large number of 

 both organic and inorganic compounds, and believe that I 

 have been able to make out numerous and varied relationships 

 between these properties. 



My first paper (Phil. Mag. [5] xviii. p. 1) dealt with the 

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

 normal halogen compounds of the elements, and I showed that 

 certain well-defined relationships existed as regards the above 

 physical properties of these compounds. My second paper 

 (ibid. [5] xx. p. 259) dealt in a similar manner with some of 

 the physical properties of the normal alkyl compounds of the 

 elements, which were shown to exhibit exactly the same rela- 

 tionships as those of the corresponding halogen compounds ; 

 proving, therefore, that the function of the alkyl radicals — 

 methyl CH 3 , ethyl C 2 H 5 , propyl C 3 H 7 , &c. — was exactly ana- 

 logous to that of the halogen elements — chlorine, bromine, 

 and iodine. 



In the present paper I wish to show that the normal ha- 

 logen and alkyl compounds of the hydrocarbon radicals exhibit 

 relationships similar to those of the corresponding compounds 

 of the elements, and therefore that the elements and hydro- 

 carbon radicals are analogous and have the same function in 

 their several compounds. In a fourth and final paper I intend 

 to take a general review of the whole question, and to draw 

 certain conclusions as to the nature of the chemical elements 

 and of the Periodic Law. 



The following table contains the experimental data, with 

 the authorities, which have been used in drawing the conclu- 

 sions given below. For the purpose of avoiding minus signs 

 all temperatures are reckoned from the absolute zero ( — 273). 

 The following abbreviations are used : — Me = methyl, CH 3 ; 

 Et = ethyl, C 2 H 5 ; Pr a = normal propyl, CH 3 . CH 2 . CH 2 — ; 

 Pr? = isopropyl (CH 3 ) 2 CH— . 



