7. The gasholder must be fitted with an appliance for removing any gas which may be generated (especially when the apparatus is first brought into action) after the available space is full. This vent must have a diameter at least equal to the inlet pipe of the holder. 8. Acetylene plant must be provided with purifying apparatus which contains a proper purifying material in a suitable condition. 9. The dimensions of subsidiary apparatus, such as washers, purifiers, condensers, pipes, and cocks must correspond with the capacity of the plant. 10. Purifiers and washers must be constructed of materials capable of resisting the attack of the substances in them. 11. Every generator must bear a plate giving the name of the maker, or the seller, and the maximum number of l0-litre lights it is intended to supply. If all the carbide put into the generator is not gasified at one time, the plate must also state the maximum weight of carbide in the charge. The gasholder must also bear a plate recording the maker's or seller's name, as well as its storage capacity. 12. Rules 1 to 11 do not apply to portable apparatus serving up to two lights, or to portable apparatus used only out of doors for the lighting of vehicles or open spaces. II. _Rules for Erection_ 1. Acetylene apparatus must not be erected in or under rooms occupied or frequented (passages, covered courts, &c.) by human beings. Generators and holders must only be erected in apartments covered with light roofs, and separated from occupied rooms, barns, and stables by a fire-proof wall, or by a distance of 15 feet. Any wall is to be considered fire- proof which is built of solid brick, without openings, and one side of which is "quite free." Apparatus may be erected in barns and stables, provided the space required is partitioned off from the remainder by a fire-proof wall. 2. The doors of apparatus sheds must open outwards, and must not communicate directly with rooms where fires and artificial lights are used. 3. Apparatus for the illumination of showmen's booths, "merry-go-rounds," shooting galleries, and the like must be erected outside the tents, and be inaccessible to the public. 4. Permanent apparatus erected in the open air must be at least 15 feet from an occupied building. 5. Apparatus sheds must be fitted at their highest points with outlet ventilators of sufficient size; the ventilators leading straight through the roof into the open air. They must be so arranged that the escaping gases and vapours cannot enter rooms or chimneys. 6. The contacts of any electrical warning devices must be outside the apparatus shed.