The appeearance of polar forms of 1,4-Dioxan at temperatures above 200°C

The total polarization of 1,4-dioxan vapour is reported for 20 temperatures between 118 and 365 �C. The results, considered together with 19 others previously recorded over a range down to 56 �C, indicate the generation of polar forms at higher temperatures, and confirm an earlier suggestion by Gibbs (1961). The variation of P with 1/T �K is shown graphically and may also be qualitatively forecast by equations having a semi-empirical character ; a steep rise of P is predicted as T is increased above about 200 �C.