268 



Prof. T. Oarnelley on the Periodic Law. 







Boiling-points. 



Specific gravities. 





Number of 

 cases in 



which the 

 rule is 



applicable. 



Number of 

 exceptions. 



Number of 

 cases in 



which the 

 rule is 



applicable. 



Number of 

 exceptions. 



Relation 1 



2 



73 

 42 

 46 

 42 

 51 

 43 

 35 

 33 

 104 



180 " 



8 

 

 2 

 1 

 

 

 

 3 

 3 



*2o" 



30 

 35 

 31 

 16 



25 

 14 



45 



19 



78 



1 

 3 

 



1 



0* 

 



3 



2 

 7 





3 



, 4 



5 



6 



, 7a 



, 7b 



8a 



, 8b 



9 





r 



Cotal 



649 



37 



= 5*7 per cent. 



293 



17 



=5*8 per cent. 







For the reasons stated in my former paper (ibid. p. 10) this 

 is a very small proportion of exceptions ; and even of these no 

 less than 14 are due to the boiling-points of TeEt 2 and SbEt 3 

 being too low, and 8 due to the specific gravity of PbEt 4 

 being too low and those of NBu 3 and SiEt 4 too high. In the 

 case of the specific gravities, some of the exceptions are 

 undoubtedly owing to these data not being all strictly com- 

 parable with one another, since they have neither all been 

 determined at the same temperature, nor at equal distances 

 from the boiling-points. 



The above facts show, therefore, that the physical properties 

 of the alkyl compounds of the elements (so far as they have 

 been investigated) obey exactly the same rules as those of the 

 corresponding halogen compounds, and would consequently 

 allow of general conclusions being drawn and practical appli- 

 cations being made similar to those indicated in my previous 

 paper (ibid. pp. 11, 14, and 19), in connection with the latter 

 compounds, and which it will not be necessary to repeat here. 



In my next communication I hope to extend these investi- 

 gations to the halogen compounds of the hydrocarbon radicals, 

 and subsequently to show how the facts thus obtained may 

 throw light on the nature and raison d'etre of the Periodic 

 Law. 



