Note:  Do not rely on this information. It is very old.

Aerostatic Press

Aerostatic Press, the name given to a machine for utilising the pressure of the atmosphere for extracting the colouring-matter from dye-woods and for other purposes. The machine is divided into two parts by means of a horizontal partition, upon which the matter from which the extract is to be obtained is laid; the partition is perforated with small holes, and a perforated lid fits over it. The liquid which is to extract the colouring-matter is then poured on the top, and the air extracted from the lower portion of the vessel by means of an air-pump, and by atmospheric pressure the extracting liquid is forced through the substance, carrying with it the required colouring-matter.