Abstract: The present invention provides a device for the determination of micro-organisms, comprising a vessel (1) closable with a cover (3) in which vessel is housed a nutrient medium carrier in the form of a longitudinal carrier body (2, 40) which has a plurality of troughs (10, 11, 12, 13, 41, 42, 45, 46) for the reception of nutrient substrate substances, the upper surfaces of which are provided with a removable cover, wherein at least one closable filler connection (19, 20, 43, 44), formed on the carrier body (2, 40) opens into each trough (10, 11, 12, 13, 41, 42, 45, 46).

Abstract: The present invention provides a Petri dish, especially for culturing micro-organisms, comprising a circular lower dish and a cover loosely laid thereon. Projections are formed provided on the periphery of the inner surface of the cover and, matching depressions are formed on the rim of the lower dish. This permits adjusting a gap between the cover and dish for control of gas exchange between the interior of the Petri dish and the atmosphere.

Abstract: In a pneumatic mixing apparatus for bulk materials, filter apparatus comprises a plurality of tube filters which are disposed each beneath a reverse cleaning nozzle. Venturi nozzles fastened to a perforated plate project into each tube filter coaxially with the latter. An external supporting frame is also fastened to the perforated plate and at its bottom end embraces the tube filters in a plurality of coplanar rings affixed to one another.