Show acetylene and air in a mixture with air the smallest mount amount of 1 acetylene e capable of propagating flame Is per cent and the largest amount Is about 73 percent according to the tests of G A burrell and G G oberfell for the united states bureau of mines unmixed with air acetylene Is explosive under a pressure of 3 to 5 atmospheres when an electric spark Is passed through it or when a platinum spiral Is heated in it Calcium carbide in a mine brings little attl risk when the material Is care carefully fully handled |