Acid egg

The terms acid egg and montejus (or monte-jus) are sometimes used interchangeably to refer to a device with no moving parts formerly used instead of a pump in order to transfer difficult liquids.

It was traditionally made of ceramic (to be corrosion resistant) and spherical in shape (to withstand the pressure) thus giving its name.

[5] In principle, the vessel is part filled with liquid, which is then expelled by pumping in compressed air.

When the acid egg is emptied, connections to the compressor and the delivery pipe are closed by valves, the air pressure is vented and the vessel refilled with acid.

Unlike the acid egg, it traditionally consists of a vertical cylindrical vessel made of steel, with a pipe from the bottom turned upwards, and it is pressurized by steam.