Iodination of N-methylquinaldinium iodide gives N-methylquinaldinium tri-iodide which with silver nitrate affords quinoline-2-aldehyde methiodide. A possible mechanism is advanced. Iodination of N-methyl-lepidinium iodide similarly yields N-methyl-lepidinium tri-iodide, but in this case silver nitrate treatment gives no aldehyde. Excess of iodine results in the diamagnetic bis(N-methyl-lepidinium)octa-iodide. The evidence obtained from absorption spectra and electrical conductivity measurements regarding ionic and intraionic dissociation of N-methylquinolinium polyiodides is discussed.