Show acetylene and air in a mixture with air tile the smallest amount of acetylene nce tylene capable of propagating flame Is per cent and the largest amount Is about 73 per cent according to the tests ests of G A burrell and G G oberfell for the united states bureau of mines unmixed with air acetylene Is e explosive under a pressure of 3 to 6 5 atmospheres spheres when an electric spark is 19 passed through it or when a platinum spiral Is heated la in it calcium carbide in a mine brings little risk when the material Is carefully handled |