ALTHOUGH fluoranthene is readily attacked by bromine, etc., none of the disubstituted products has been rigidly orientated. Tobler et al.1 obtained a fluoranthene disulphonic acid, which on fusion with alkali followed by oxidation gave a coloured ‘chin-hydronartigen’ compound, and they rightly pointed out that a quinoid product would mean that sulphonation had occurred at the 4 : 11-positions. Their evidence, however, is not conclusive and experimental details are lacking.