A mixture of gases that, in the liquid phase, shall conform to the following: (1) methylacetylene-propadiene (in combination, with a maximum ratio of 3. 0 moles of methylacetylene per mole of propadiene in the initial liquid phase in a storage container) — 68 mole percent maximum; (2) propane, butane, isobutane (in combination) — 24 mole percent minimum, of which at least 1⁄3 (8 mole percent of total mixture) shall be butane or isobutane; (3) propylene — 10 mole percent maximum; (4) butadiene — 2 mole percent maximum.