SOURCES OF ENERGY 183 



peared in the primaeval atmosphere as a result of the action 

 of electric discharges was markedly augmented both in quan- 

 tity and quality by the action of ultraviolet radiation. Owing 

 to the selective activity of radiant energy on the surface of 

 the Earth new organic compounds appeared continually, and 

 the complication of their molecular structure was increasing 

 the whole time. 



Methane absorbs ultraviolet radiation in the neighbour- 

 hood of 1,400 A, and especially strongly in the neighbourhood 

 of 1,295 ■^•^"" When this happens, it is split to methyl radicals 

 and atomic hydrogen. The final products of these trans- 

 formations of methane are hydrogen and acetylene as well as 

 ethylene, ethane and hydrocarbons with three, five and six 

 carbon atoms. ^^^ 



According to S. Tolloczko,^" when ethane is submitted 

 to ultraviolet irradiation it forms a light, colourless con- 

 densate made up of a mixture of hydrocarbons, chiefly hex- 

 ane, and a gas containing hydrogen and methane. When 

 ethylene is decomposed by ultraviolet radiation having a 

 wavelength shorter than 2,100 A, acetylene and hydrogen are 

 formed.^" 



D. Berthelot and H. Gaudechon^^* observed a slow poly- 

 merisation of ethylene under ultraviolet irradiation. Accord- 

 ing to H. S. Taylor and D. G. HilP-' the polymerisation of 

 ethylene may lead to the formation of saturated hydro- 

 carbons, in particular to those of very high molecular weight 

 such as cuprene. 



Acetylene also polymerises very easily and, under the 

 influence of idtraviolet irradiation, it gives rise to many 

 products, including benzene and naphthalene.^-^ 



Ethylene, acetylene and their derivatives may readily be 

 oxidised photochemically by oxygen to form aldehydes, 

 ketones and acids. For example, on irradiation in the 

 presence of oxygen ethylene gives rise to formic acid^^^ and 

 acetylene to oxalic acid and formaldehyde.^-* The oxidation 

 products can react with the hydrocarbons and their deriva- 

 tives to give more and more complicated organic substances 

 such as allyl alcohol, crotonic, maleic and tartaric acids, etc. 



Ammonia absorbs ultraviolet light at wavelengths below 

 2,400 A. The maximum absorption is at 1,910- 1,935 ^-^^^ 



