If the generator should leak and the leak cannot be stopped by screwing the nuts and valves tight, the stuffing-boxes need repacking with hemp, etc., as already directed for other parts. If the acid chamber is leaking, screw the plunger down until it ceases to leak. When, however, the leak cannot be stopped, it needs looking after.

The collapsing of linings in apparatus is liable to occur whenever by the formation of a partial vacuum the pressure in a generator or cylinder falls below the atmospheric pressure. It is liable to be caused by drawing off the contents of generator or cylinders, without pressure, through the lower bung or cock without opening the upper bung as a vent; or by tightly closing a generator or cylinder, without pressure, whether partially full of water, or containing only gas or air, when the temperature is falling. It is frequently caused by suddenly discharging the residue in generator under a high pressure, and is felt when the agitator either can be no more turned or occasions friction with the collapsed lining in turning.

To replace a collapsed lining it is recommended to put in a heavy charge of gas, say 200 pounds, and allow it to stand several hours. Or, with a force-pump, pump in water to 200 pounds pressure and allow it to remain several hours.