The acid-catalyzed condensation of a number of aromatic compounds with formaldehyde or formaldehyde derivatives is known to yield diarylmethanes under the proper conditions. This reaction is similar to the process of chloromethylation studied in a previous publication,'the benzyl type of carbonium ion being a possible intermediate in both processes. The similarity of the two reactions is borne out by the frequent appearance of diarylmethanes as by- ...