At very low temperatures, a mixture of gaseous para-and ortho-hydrogen, on account of the 9-fold degeneracy of the oH2 component, constitutes a 10-component mixture. The treatment of its transport properties by the Chapman-Enskog theory can be reduced to that of a binary mixture. In a 1 pH2 : 9 oH2 mixture, the viscosity and heat conductivity are those of a 10-fold degenerate simple gas, and there is no thermal diffusion. The results are extended to multi-component mixtures with components having degeneracies sinilar to that of oHm. Β§ 1. Introduction. In a recent article 1) the authors, in collaboration with Van Leeuwen, Roos and De Boer, published the results of some calculations on the transport properties and the equation of state of mixtures of gaseous para-and ortho-hydrogen at temperatures below 400 K. These mixtures were treated as binary para-ortho-mixtures, the degenerate states of' the oH2 molecules showing up only in the special form of the crosssections holding for the orig. component. In the present article, we shall discuss this question in more detail. *) In 8), eq. (I 1), s -z --(I --ccl0c's/yi a) should be replaced by ~i~'s/yz z. **) In 5), Anhang I, p. 294, the definition of q should contain a factor 8/9 instead of I0/9; coefficients in the definition of s should not read (16/25, 96/5, 16125) but (128/225, 32/15, 16/225).