It was concluded on the basis of the similarity between the electronic spectra of difurylarylmethanes and trifurylalkanes and the spectra of the corresponding arylfurylcarbinols and difurylcarbenium perchlorates in concentrated sulfuric acid that the appearance of color in the solutions of polyfuryl(aryl)alkanes in concentrated sulfuric acid results from their disproportionation at the carbon-carbon bond with the elimination of the furan ring. The disproportionation of difurylalkanes, containing a methine hydrogen atom at the central carbon atom, under these conditions is accompanied by hydride transfer.For Communication 13, see [1].Kubansk State Technological University, Krasnodar. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 738–741, June, 1996. Original article submitted February 21, 1996.