1.It was found that 1,1,2-trimethylcyclopropane, passed at 220‡ over platinized or palladized charcoal at a space velocity of 0.2 hour−1, is isomerized to the extent of about 60% into a mixture of olefins.2.It was shown that, in absence of catalyst, the hydrocarbon remains unchanged under these conditions.3.It was found that in isomerization the point of bond rupture in the ring is different from that found in hydrogenolysis: the bonds attached to the quaternary carbon atom are broken, mainly the bond between the most and least hydrogenated atoms of the r