2. A drawing and description of the construction of the apparatus and a short explanation of the method of working it must be fixed in a conspicuous position under cover in the apparatus house. The notice must also contain approved general information as to the properties of calcium carbide and acetylene, precautions that must be observed to guard against possible danger, and a statement of how often the purifier will require to be recharged. 3. The apparatus must be marked with the name of the maker, the year of its construction, the available capacity of the gasholder, and the maximum generating capacity per hour. 4. Each constituent of the plant must be proportioned to the maximum hourly output of gas and in particular the available capacity of the holder must be 75 per cent. of the latter. The apparatus must not be driven above its nominal productive capacity. 5. The productive capacity of generators in which the gasholder has to be opened or the bell removed before recharging, or for the removal of sludge, must not exceed 50 litres per hour, nor may the charge of carbide exceed 1 kilo. 6. Generators exceeding 50 litres per hour productive capacity must be arranged so that they can be freed from air before use. 7. Generators exceeding 1500 litres per hour capacity must be arranged so that the acetylene, contained in the parts of the apparatus which have to be opened for recharging or for the removal of sludge, can be removed before they are opened. 8. Automatic generators of which the decomposing chambers are built inside the gasholder must not exceed 300 litres per hour productive capacity. 9. Generators must be arranged so that after-generation cannot produce objectionable results. 10. The holder of carbide-to-water generators must be large enough to take all the gas which may be produced by the introduction of one charge of carbide without undue pressure ensuing. 11. The maximum pressure permissible in any part of the apparatus is 1.1 atmosphere absolute. 12. The temperature in the gas space of a generator must never exceed 80° C. 13. Generating apparatus, &c., must be constructed in a workmanlike manner of metal capable of resisting rust and distortion, and, where the metal comes in contact with carbide or acetylene, it must not be one (copper in particular) which forms an explosive compound with the gas. Cocks and screw connexions, &c., of brass, bronze, &c., must always be kept clean. Joints exposed to acetylene under pressure must be made by riveting or welding except that in apparatus not exceeding 100 litres per hour productive capacity double bending may be used. 14. Every apparatus must be fitted with a safety-valve or vent-pipe terminating in a safe place in the open, and of adequate size. 15. Every apparatus must be provided with an efficient purifier so fitted that it may be isolated from the rest of the plant and with due consideration of the possible action of the purifying material upon the metal used.