Abstract: A machine is disclosed for printing and/or otherwise processing blanks of sheet material in which the interior of the machine is pressurized to a super-atmospheric pressure such that the blanks are forced firmly against the transfer conveyor between sections of the machine and dust in the ambient air is prevented from entering the machine and contaminating the print function.

Abstract: A device is disclosed for receiving a disposable pipette tip, aspirating a supply of liquid into the pipette and dispensing the liquid in precise predetermined dosages. The device comprises a housing, a cylindrical passage within the housing, a piston extending into the passage from the rear end thereof and a plunger extending rearwardly from the piston. Actuating means are disposed within the housing for advancing the plunger forward in discrete amounts and a trigger extends from the housing operatively engaging the actuating means. The device further includes means for disengaging the actuating means whereby the plunger may freely be moved forward and back to permit a supply of liquid to be aspirated into the pipette. A detipping mechanism is also provided which permits a pipette tip to be removed without requiring any handling of it.