The capillary constant a(2) has been measured by the differential capillary-rise technique and the surface tension a of dimethyl ether and n-butane has been determined with the use of data on the densities of saturated liquid and gas. The experiments with dimethyl ether were performed at temperatures from 214 K to 390 K, for n-butane from 278.15 K to 423.04 K. Equations that approximate the temperature dependences of a(2) and a have been suggested. (C) 2016 Published by Elsevier B.V.