[en] The electron drift velocity (W) and the product of the gas number density and the electron longitudinal diffusion coefficient (N D_L) were measured in the ranges of E/N over 1.4-100 Td in the 0.468% c-C₄F₈/Ar mixture, 8-100 Td in the 4.910% c-C₄F₈/Ar mixture, and 170-1000 Td in pure c-C₄F₈, by using a double-shutter electron drift apparatus with variable drift length (1-10 cm). The measured electron transport coefficients in these mixtures indicated that the inelastic processes between electrons and the c-C₄F₈ molecules had a strong influence and the measured electron drift velocity in pure c-C₄F₈ showed substantial deviation from the reported results in the high E/N range. There are no measurements on ND_L in pure c-C₄F₈