Show acetylene and air in a mixture alth nith air the smallest amount of nce tlene capable of propagating name Is per cent and the largest amount Is about 73 per cent according to the tests of G A burrell and G G oberfell for the united states bureau of mines mine unmixed with air aceta acetylene lene li Is explosive under a pres ture sure of 3 to 5 atmospheres when an electric spark Is pissed through it or when a platinum spiral Is heated in it calcium carbide in a mine brings brines little risk when tile the material Is carefully handled bandied |