hydrogen fluoride in hydrogen fluoride anh. HF added at -196°C, the mixt. kept at -78°C for 15 h, at -45°C for 2 h; CsSbF6 ppt. sepd. from NF4SClO4 soln., HF pumped off, the solid residuewarmed to room temp., de gaseous decompn. products sepd. by fractional condensation;
