This is what I've found after looking for several days at
dozens and dozens of sites:
"MAPP gas is a trademarked name, belonging to The Linde Group,
and previously belonging to the Dow Chemical Company, for a
fuel gas based on a stabilized mixture of methylacetylene
(propyne) and propadiene. The name comes from the original
chemical composition, methylacetylene-propadiene propane.
MAPP gas is also widely used as a generic name for UN 1060
stabilised methylacetylene-propadiene (unstabilised
methylacetylene-propadiene is known as MAPD). MAPP gas is
widely regarded as a safer and easier-to-use substitute for
acetylene. In the spring of 2008, true MAPP gas production
ended in North America when production was discontinued at
the only remaining plant in North America that still
manufactured it. Current products labeled "MAPP" are, in fact,
MAPP substitutes. These versions are stabilized liquefied
petroleum gas (LPG) with high levels of propylene."
dg
