202 Scientific Proceedings, Royal Dublin Society. 



order of their reactivities as measured by silver nitrate, with the 

 single exception of methyl iodide, which appeared to possess a 

 rate of decomposition intermediate between isopropyl and ethyl 

 iodides. After six months the colorations, as roughly judged by 

 eye, were as follows : — 



Isopropyl iodide ) _ 



Methyl iodide }' ' ' ' Deep Wn - 



Ethyl iodide ) 



-r, , . ,., >, . . . Intense yellow. 

 %-rropyl iodide ) J 



w-Butyl iodide ) _ _ ,. 



T , . ,., >, . . . rale yellow. 



Isoamyl iodide ) J 



Isobutyl iodide, . . . Colourless. 



If this list be compared with the table of reactivities, as given 

 on page 197, the general parallelism is unmistakable. The 

 exceptional position occupied by methyl iodide is very peculiar,, 

 considering its relatively low reactivity. 



Eoyal College of Science, Dublin. 

 February, 1904. 



