Aerostatic Press

Aerostatic Press. This is a machine used in extracting the colouring-matter from dye-woods and such like. A vessel is divided by a horizontal partition pierced with small holes. Upon this the substance containing the colour is laid, and a cover, also perforated, is placed upon it. The extracting liquid is then poured on the top, and the air being drawn from the under part of the vessel by a pump, the liquid is forced through the substance by the pressure of the atmosphere.