Summary 1. Ethylidene hydrocarbons of the general formula CHICH (CsH4R) 2 have been prepared from acetylene in the presence of concentrated H2S04 and HgO from the following benzene derivatives: propyl-and isopropylbenzenes, n-butylbenzene, tert.-butylbenzene, methylethylphenylmethane, methylisopropylphenylmethane, diethylphenylmethane. These are all viscous, amber colored liquids of high boiling points, excepting ethylidenebis-tert.- ...