Liquid crystal mixtures

A nematic liquid crystal mixture having positive anisotropy of the dielectric constants which comprises a nematogenic mixture with a clearing point above 60.degree. C. and one or more solvents individually selected from the group consisting of a straight-chain alkane of 8-16 carbon atoms, an alkyl halide of 6-16 carbon atoms, a dialkyl ether of 4-8 carbon atoms in each alkyl radical, a dialkyl carbonate of 2-7 carbon atoms in each alkyl radical, an alkanecarboxylic acid alkyl ester the alkyl radicals of which together contain 6-16 carbon atoms, p-xylene, 1-phenylheptane, p-octylbenzoic acid methyl ester, p-hexylbenzaldehyde, and a compound of the formula ##STR32## wherein R.sub.14 and R.sub.15 are straight-chain alkyl containing, together, a total of not more than 14 carbon atoms or R.sub.14 is straight-chain alkyl and R.sub.15 is straight-chain alkoxy containing, together, a total of not more than 8 carbon atoms, provided said nematogenic mixture contains at least one compound selected from the formula ##STR33## wherein one of R.sub.8 and R.sub.9 is hydrogen, straight-chain alkyl containing 1 to 7 carbon atoms, straight-chain alkoxy containing 1 to 7 carbon atoms or straight-chain alkanoyloxy containing 2 to 7 carbon atoms and the other is cyano and one of X, Y and Z is nitrogen and the other two are CH.