30 Papers. 



The apparatus consisted of a distillation-flask containing the alkyl iodide 

 and pkosphorus-pentoxide, two U tubes containing the same drying 

 reagent, a further U tube containing carefully dried copper-oxide, and an 

 upright condenser connected to a receiver with suitable guard-tubes. 

 Between the distillation-flask and the first drying-tube was interposed a T 

 piece that allowed the entry of dry carbonic acid. After the whole ap- 

 paratus had been sealed together, glass to glass, the various U tubes were 

 heated to the required temperature and the apparatus exhausted. Dried 

 carbonic-acid gas was then allowed to stream in, and, in order to insure 

 the complete absence of oxygen, as well as complete drving, this opera- 

 tion was repeated about thirty times. 



A preliminary experiment showed that at a temperature of 310° G. the 

 oxide reacted quickly with the iodide, while at this temperature the vapour 

 of the volatile alkyl compound suffered no decomposition. The rate at 

 which the iodide distilled could be readily controlled, and it was generally 

 so regulated that about 80 grammes were distilled over in 45 minutes. 



A few experiments sufficed to show that the reaction, instead of taking 

 the course represented by the equation CuO -f- 2 CH 3 I = Cul 2 -f (CH 3 ) 2 0, 

 took a much more complex path, the ultimate solid product invariably 

 being cuprous iodide. Since not the slightest liberation of iodine was noted, 

 as would occur were the cuprous iodide formed by the decomposition of 

 the unstable cupric salt, it is to be concluded that cuprous iodide is the 

 primary product of the reaction. 



Numerous other products of the reaction were also obtained. The 

 distillate always gave a strong aldehyde reaction, and it was also possible 

 to collect a considerable quantity of gas. This proved to contain oxygen, 

 carbon-monoxide, ethylene, methane, and its homologues. When methyl- 

 iodide was used, the first three gases were contained to the extent of about 

 3 per cent., while the methane series bulked very largely in the total. The 

 substitution of ethyl-iodide for methyl-iodide caused a marked change in the 

 ratio of saturated to unsaturated hydrocarbons, for the percentage of ethy- 

 lene rose to about 50 per cent., while the saturated hydrocarbons fell from 

 about 90 to 45 per cent. 



6. The Nature of Gamma Rays. 



By "Professor T. H. Laby and P. W. Burbidge, B.Sc. Senior University 



Scholar. 



| Read before the Wellington Philosophical Society, 12th July, 1911.'] 



Dr. E. von Schweidler pointed out in 1905 that an effect such as ioniza- 

 tion by a rays due to a finite, number of independent events would be subject 

 to fluctuations. The mathematical theory of the different experiments 

 which have been made with light, a and /? rays, has been developed by 

 Mr. N. R. Campbell. 



One of us began some preliminary experiments in 1908 at the Cavendish 

 Laboratory to detect discontinuous effects with y rays. Two forms of 

 apparatus have been used in our experiments. In the first two similar 

 cylindrical ionization- vessels were placed close together with their axes 

 directed to the source of the y rays — some radium. If the y rays have 





