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Gaseous acetylene at pressures of about 200 Torr was irradiated with y-rays at doserates between about 10" and 1012 eV/cc s, with and without an electric field applied. The deposition of cuprene on the bottom of the reaction vessel was markedly affected by the field, but the rate of cuprene formation as measured by the pressure decrease was unchanged. Examination of the cuprene deposit with an electron microscope showed it to consist of rather uniform spheres averaging about 3000 A in diameter, with each containing an estimated 2 x lo8 molecules of acetylene. The mechanism of cuprene formation is discussed, and it is suggested that it does not proceed through a direct polymerization of acetylene, but involves a secondary polymerization of polyene intermediates, in the gas phase and after their condensation in liquid droplets.On a irradie de l'acetylene gazeux k des pressions d'environ 200 Torr avec des rayons-y, a des vitesses de dosage se situant entre 10" et loiZ eV/cc s, avec et sans l'application d'un champ Clectrique. La formation de dCpBt de cuprene au fond du recipient de reaction Ctait grandement affectke par la prCsence du champ, mais la vitesse de formation de cupr6ne telle que mesuree par la diminution de la pression, est demeuree inchangee. Un examen du dtp6t de cuprene au microscope CIectronique a rCvBlC que celui-ci consiste en spheres plutBt uniformes, d'un diametre d'environ 3000 A, contenant chacune un nombre estime a 2 x 10' molCcules d'acetylene. On discute du mecanisme de formation du cuprene et on suggere que celle-ci ne se dtroule pas selon la polymCrisation directe de I'ethylene, mais qu'elle implique plut6t une polym6risation secondaire d'intermediaires polyenes, dans la phase gazeuse et apres leur condensation dans les gouttelettes liquides.

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