92 Prof. V. B. Lewes. [Feb. ], 



mum expansion is reached, so that 7 c.c. of dry ethylene gave, after 

 decomposition, 12'25 c.c. They noted also that the residual hydrogen 

 had an unpleasant smell, and burnt with a slightly luminous flame. 



Berthelot,* in 1869, claims that ethylene breaks up under the 

 influence of heat into acetylene and hydrogen, as expressed by the 



equation 



CjH 4 = CjHj-f-Hj, 



and shows that the acetylene then polymerises into benzene, styrene, 

 and other liquid products of higher boiling points. Naphthalene was 

 also formed by the direct condensation of styrene and acetylene. He 

 also points out that during the heating of ethylene a large propor- 

 tion of ethane was formed, and his final conclusion is that the heating 

 of ethylene results in the splitting up of 2 mols. of ethylene into 

 acetylene and ethane, and that the formation of solid and liquid pro- 

 ducts is due to the subsequent condensation of the acetylene. 



In 1886f Day made a number of experiments in order to determine 

 the lowest point of temperature at which the constitution of ethylene 

 undergoes alteration, and the nature of the changes taking place at 

 that temperature. In order to do this, he devised an ingenious ap- 

 paratus in which the ethylene could be heated for very long periods 

 in a hard-glass tube. From these experiments he concluded that 

 when the action is continued over a long period the gas undergoes 

 change at much lower temperatures than had been previously ob- 

 served. The alteration in constitution commences at about 350 C., 

 at which temperature the change is one of condensation without the 

 formation of members of any series of hydrocarbons having a per- 

 centage of hydrogen and carbon different from ethylene, whilst if 

 ethylene is maintained at 400 for a sufficient length of time, it is 

 entirely decomposed, marsh gas, ethane, and liquid products being 

 obtained. 



In the same year Messrs. Morton and NoyesJ made an elaborate 

 investigation with the object of determining whether crotonylene, 

 CtH t) which is present in small quantities in illuminating gas and 

 other products of the distillation of organic matter, is formed as a 

 primary product of decomposition by heat, or as a secondary product 

 of the action of heat upon ethylene. 



Coal gas was passed slowly through a hard glass tube 15 mm. in 

 diameter, which was maintained at a low red heat for a distance of 

 60 cm. The products issuing from this tube were first passed 

 through a series of \J -tubes surrounded by a freezing mixture; the 

 products which were not condensed were passed through an am- 

 moniacal solution of cuprous chloride, to absorb hydrocarbons of the 



* ' Annales de Chimie et de Physique,' 4th series, vol. 16, p. 144. 

 t ' American Chemical Journal,' vol. 8, p. 153. 

 J Ibid., vol. 8, p. 362. 



