Prof. T. Carnelley on the Periodic Lata. 



509 



Table V. — Illustrating Relations 5 and 6. 







Br— CI. 



I— Br. 



I— CI. 



Et— Me. 



Pr— Et. 



Pr— Me. 





Diff. in 

 at. wts. 



} 44-5 



47 



91-5 



14 



14 



28 





B.P. 



B.P. 



B.P. 



B.P. 



B.P. 



B.P. 



/ 



Normal halides 

 and alkides of 

 Group VII. * 

 CH 3 .(CH 2 )„.X. 



V 



OH 3 ... 

 C 2 H 5 ... 

 C 3 H 7 ... 

 C 4 H 9 ... 

 5 H U ... 

 C 6 H 13 ... 

 7 H 15 ... 

 8 H 17 ... 



29 

 27 

 25 

 22 

 22 

 22 

 20 

 20 



37 

 33 

 31 

 30 



27 

 26 



22 



66 

 60 

 56 

 52 

 49 

 48 

 42 



29* 



37 

 33 



27 

 27 

 24 

 24 



29* 



37 



33 



27 



27 



24 



24 



22 



"66* 



70 

 60 

 54 

 51 



48 

 46 



Normal halides j 



and alkides of I 



Group VI. j 



X.(OH 2 ) n .X. 1 



(OH 2 )« 



(C 2 H 4 )» 



(0 3 H 6 )ii 

 (C,H 8 )ii 

 (C 5 H 10 )ii 

 (C 6 H 12 )ii 



55 

 48 

 45 

 45 

 36 

 23 



83 



a. 60 



49 







138 



a. 108 



94 



66* 



70 



60 



54 



51 



48 



61 

 54 

 51 

 48 

 46 

 41 



124 

 124 

 111 



102 

 97 



89 



* These four exceptions are all due to the boiling-point of propane, C 3 H 8 , 

 being taken too high. The number used is based on the data given by 

 Lefebvre, who states that propane is condensed to a liquid at — 25° to 

 -30° C. 



Relation 7. (a) The differences hetween the boiling-points 

 [and also between the melting-points) of the halogen {or of the 

 alky I) compounds of the hydrocarbon radicals of each group 

 diminish as we pass from the chlorides to the bromides, and 

 thence to the iodides (or from the methides to the ethides, and 

 thence to the propides, fyc). (See Table VI.) 



(b) These differences also increase as the difference between 

 the atomic weights of each pair of hydrocarbon radicals increases. 

 (See Table VI.) 



In those cases where there is a common difference between the 

 atomic weights of several pairs of hydrocarbon radicals, then the 

 differences between the boiling-points increase as the sum of the 

 atomic weights of the several pairs of hydrocarbon radicals 

 diminishes. (See Table VI.) 



