Regulation 19
No person shall fire a shell or a round of shells unless he has carried out with respect to it immediately before firing an examination for general safety and tests for the presence of inflammable gas in any accessible place within thirty feet of a shot hole or any of them.
Every such test for inflammable gas shall be made with a locked flame safety-lamp of a type approved by the Minister for the purpose of deputies' inspections, a methanometer of a type approved by the Minister or other apparatus of a type approved by the Minister for the purpose.
No person shall fire a shell if on any such test made with respect to it he finds a percentage of inflammable gas exceeding one and a quarter per cent. or he can see an indication of gas on the lowered flame of a safety-lamp.