Abstract (1) The quantities of seven following simple gases and six gaseous mixtures flowing through the capillary have been measured at the pressures between 4 and 0.01mm. &H_2,C_2H_2,C_3H_6,H_2∼C_3H_6; &C_6H_6,CCl_4,CHCl_3,(C_2H_5)_2O,C_6H_6∼CCl_4,CCl_4∼CHCl_3, &(C_2H_5)_2O∼CHCl_3. (2) The quantities of flow, K, is a function of the mean pressure, p, and the K−p curve passes through a minimum point. The occurrence of a minimum point of mixtures is more remarkable than in the case cf simple gases. (3) The quantities of flow of simple gases are satisfactorily expressed by K=ap+γb, where γ is a coefficient which becomes a constant at higher pressures (=0.9) or at very low pressures (=1.0), and varies from 0.9 to 1.0 at the intermediate conditions. (4) The quantities of flow of mixtures are also expressed by a formula analogous to that of simple gases. The values of γ′ at higher pressures of the mixtures are constant for varying compositions of the same combination of components, but different from those for different combinations and simple gases. These values are also considered to depend on the chemical configurations of two components. (5) The viscosities of the following mixtures have been calculated from the quantities of flow. C_6H_6CCl_4, CCl_4∼CHCl_3, (C_2H_5)_2O∼CHCl_3. The mixture CCl4∼CHCl3 shows a maximum at about 50% of CHCl3 and the viscosity curves of the other two are nearly straight.