We have studied the polymerization of ketene in the gaseous and liquid phases and in solution. Ketene does not appear to polymerize appreciably in the gas phase at room temperature. Polymerization only sets in at one or more points on the surface of the vessel after the gaseous ketene has stood for several hours. The pure liquid is stable at-80'but at 0" polymerization is rapid and is complete in about one and one-half hours.
