Prof. T. Carnelley on the Periodic Law. 



507 



Relation 2. The melting-points and boiling-points of either 

 the halogen or alkyl compounds of any hydrocarbon radical 

 increase as we pass from the chloride to the bromide and thence 

 to the iodide ; or from the methide to the ethide, and thence to 

 the propide, fyc. (See Tables II. and III.) 



Table III. — Illustrating Relations 2 and 3. 





Halogen 



com- 

 pounds. 



Chlorides. 



! 



Bromides. 



Iodides. 



M.P. 



B.P. 



M.P. 



B.P. 



M.P. 



B.P. 



/ 



CH 3 ... 



! Liquid. 



249 



Liquid. 



278 



Liquid. 



315 



„ 



C 2 H 5 ... 



; Liquid. 



285 



Liquid. 



312 



Liquid. 



345 



Normal primary 



C 3 H 7 ... 



; Liquid. 



319 



Liquid. 



344 



Liquid. 



375 



halides of 



4 H 9 ... 



Liquid. 



351 



Liquid. 



373 



Liquid. 



403 



Group VII. J 



5 H U ... 



Liquid. 



380 



Liquid. 



402 



Liquid. 



429 



CH 3 .(CH 2 ) H .X. 



6 H ]3 ... 



Liquid. 



406 



Liquid. 



428 



Liquid. 



454 



[ 



7 H 15 ... 



Liquid. 



432 



Liquid. 



452 



Liquid. 



474 



C 8 H 17 ... 



Liquid. 



456 



Liquid. 



476 



Liquid. 



a. 494 





Alkyl 















com- 



Meth 



[DES. 



Ethi 



DES. 



a-PROPiDES. 





pounds. 













Normal primary 



CH 3 ... 

 0,H 5 ... 





Gas. 

 245 



Liquid. 



245 

 274 



Liquid. 

 Liquid. 



274 

 311 



flrmin VTT \ 



3 H 7 ... 



Liquid. 



274 



Liquid. 



311 



Liquid. 



344 



CH 3 .(CH 2 )„.X. 



4 H 9 ... 



Liquid. 



311 



Liquid. 



344 



Liquid. 



371 



C. 5 H n ... 



Liquid. 



344 



Liquid. 



371 



Liquid. 



398 



f 



(OH 2 y 





245 



Liquid. 



311 



Liquid. 



371 



Normal alkides 



(C 2 H 4 )" 



Liquid. 



274 



Liquid. 



344 



Liquid. 



398 



of Group VI. < 



(C 3 H 6 )" 



Liquid. 



311 



Liquid. 



371 



222 



422 



X.(0H 2 )„.X. 



(C 4 H 8 )" 



Liquid. 



344 



Liquid. 



398 



241 



446 



1 



(O,H 10 )" 



Liquid. 



371 



222 



422 



247 



468 



Relation 3. The melting- and boiling-points of either the 

 halogen or alkyl compounds of the hydrocarbon radicals of any 

 one group increase as the atomic weight of the hydrocarbon 

 radical increases. (See Table III.) 



Relation 4. The differences between the boiling-points (and 

 also between the melting-points) of the chlorides and bromides, 

 bromides and iodides, chlorides and iodides {or betiueen those of 

 the methides and ethides, ethides and propides, propides and 

 butides, 8fc.\ increase algebraically from the first member of each 

 series of hydrocarbon radicals up to the fourth or middle (tetrad) 



