7. Acetylene plants must be prevented from freezing by erection in frost- free rooms, or by the employment of a heating apparatus or other suitable appliance. The heat must only be that of warm water or steam. Furnaces for the heating appliance must be outside the rooms containing generators, their subsidiary apparatus, or holders; and must be separated from such rooms by fire-proof walls. 8. In one of the walls of the apparatus shed--if possible not that having a door--a window must be fitted which cannot be opened; and outside that window an artificial light is to be placed. In the usual way acetylene lighting may be employed; but a lamp burning paraffin or oil, or a lantern enclosing a candle, must always be kept ready for use in emergencies. In all circumstances internal lighting is forbidden. 9. Every acetylene installation must be provided with a main cock, placed in a conveniently accessible position so that the whole of the service may be cut off from the plant. 10. The seller of an apparatus must provide his customer with a sectional drawing, a description of the apparatus, and a set of rules for attending to it. These are to be supplied in duplicate, and one set is to be kept hanging up in the apparatus shed. III. Rules for Working the Apparatus. 1. The apparatus must only be opened by daylight for addition of water. If the generator is one of those in which the entire charge of carbide is not gasified at once, addition of fresh carbide must only be made by daylight. 2. All work required by the plant, or by any portion of it, and all ordinary attendance needed must be performed by daylight. 3. All water-seals must be carefully kept full. 4. When any part of an acetylene apparatus or a gas-meter freezes, notwithstanding the precautions specified in II., 7, it must be thawed only by pouring hot water into or over it; flames, burning fuel, or red- hot iron bars must not be used. 5. Alterations to any part of an apparatus which involve the operations of soldering or riveting, &c., _i.e._, in which a fire must be used, or a spark may be produced by the impact of hammer on metal, must only be carried out by daylight in the open air after the apparatus has been taken to pieces. First of all the plant must be freed from gas. This is to be done by filling every part with water till the liquid overflows, leaving the water in it for at least five minutes before emptying it again. 6. The apparatus house must not be used for any other operation, nor employed for the storage of combustible articles. It must be efficiently ventilated, and always kept closed. A notice must be put upon the door that unauthorised persons are not permitted to enter. 7. It in forbidden to enter the house with a burning lantern or lamp, to strike matches, or to smoke therein. 8. A search for leaks in the pipes must not be made with the aid of a light.