504 



Prof. T. Carnelley on the Periodic Law. 





Series 1. 



Series 2. 



Series 3. 



Series 4. . 



Series 5. 





Group I .... 







(C 3 H)X, 



(C 4 H 3 )X, 



(C^X, 





„ il... 





(cyx 2 



(0 3 H 2 )X 2 



(C 4 H 4 )X 2 



(C 5 H e )X 2 



$ -2 



„ in.... 





(C 2 H)X 3 



(0 3 H3) X 3 



(0 4 H 5 )X 3 



(0 5 H 7 )X 3 





„ IV.... 



cx 4 



(C 2 H 2 )X 4 



(C 3 H 4 )X 4 



(C 4 H 6 )X 4 



(0 5 H 8 )X 4 



00 o 



„ v.... 



(CH)X 3 



(C 2 H 3 )X 3 



(0 3 H 5 )X 3 



(C 4 H 7 )X 3 



(0 3 H 9 )X 3 





„ VI.... 



(CH 2 )X 2 



(C 2 H 4 )X 2 



(C 3 H 6 )X 2 



(C 4 H 8 )X 2 



( C 5H]o) X 2 



as "—j 



>2 £ 



„ VII. ... 



(OH 3 )X 1 



(0 2 H 5 )X t 



(C 3 H 7 )X 1 



(0 4 H 9 )X 



(0 5 H n )X, 



<d '53 

 w. 



In the above, X=C1, Br, I, CH 3 , C 2 H 5 , or C 3 H 7 , &c. 



The above series, of course, might be considerably extended ; 

 but I have not thought it necessary to carry my investigations 

 beyond the 8th series for the halogen compounds, nor beyond 

 the 5th series for the alkyl compounds*. 



When there are several isomeric modifications of the same 

 empirical formula, only those which are strictly analogous 

 should be compared ; thus, normal compounds should be com- 

 pared with normal, and iso-compounds with iso-, &c. In 

 some instances, however, this is not possible, owing to the 

 data being incomplete, or to the constitution being unknown, 

 or when the compounds belonging to different groups of the 

 same series are to be compared ; in this case the mean of the 

 melting- or boiling-points of the several isomeric compounds 

 is employed. As a general rule, however, the same results 

 are obtained, no matter whether we use the mean melting- or 

 boiling-point for all the isomeric compounds, or whether we 

 compare only those compounds which are strictly analogous. 



Now the same general rule that we have already shown 

 (ibid, xviii. p. 2) to hold good as regards the corresponding 

 compounds of the elements also holds in the case of the above 

 hydrocarbon radicals ; for in whatever way we may arrange 

 the melting- or boiling-points of their normal halogen or 

 alkyl compounds, provided only that we arrange them syste- 

 matically, we always find that certain definite and regular 

 relations may be traced between them. The following are 

 examples of such relations : — 



Relation 1. If the above hydrocarbon radicals be arranged 

 in the order of their atomic weights, then the melting -points and 

 boiling joints of both their halogen and alkyl compounds rise 

 and fall periodically. 



This periodicity is such that the values increase from the 



* The metliide curve in the diagram which accompanies the paper has, 

 however, been completed to the end of the eighth series. 



