Abstract: Means for reducing intersample contamination in an automatic chemical testing apparatus, in which liquid from a sample is aspirated from a sample source into a reservoir, and aliquots of the sample are each dispensed into individual reaction containers for analysis by well-known means. A cylindrical reservoir is utilized with a piston therein shaped for pushing out virtually all of the remaining sample from the cylinder after dispensing the sample liquid through a hollow needle, communicating with the cylinder. A solid pin coaxially mounted within the piston is projected through the needle and has minimum clearance therewith, for pushing remaining sample out of the needle. The portion of the pin projecting through the needle is retracted into the piston prior to aspiration of liquid from a next sample.

Abstract: An elongated cylinder having a hollow cylindrical extension member received press fit in a discharge open end thereof normally receives an elongated plunger in an opposite receiving open end with said plunger having a piston-like end within the cylinder selectively slideable along the cylinder to dispense fish bait of putty-like consistency from the cylinder through the extension member. The cylinder preferably has a uniform outer cylindrical surface except for an annular, outwardly projecting portion at the plunger receiving end thereof and a finger gripping ring is telescoped over the cylinder outer surface selectively slideable therealong movable to the cylinder plunger receiving end against the outwardly projecting portion for normal bait dispensing use of the cylinder and plunger, but movable to the cylinder discharge end for removal of the plunger from the cylinder and insertion of the cylinder plunger receiving end into a supply of fish bait to fill the same.

Abstract: A dosing apparatus is provided which is adapted to aspirate and dispense a first fluid in predetermined amounts. The apparatus includes an elongated tubular member which is connected at one end to a reversible pump for imparting controlled reverse flow of a second fluid within the tubular member during aspirating and dispensing of the first fluid from the opposite end of the tubular member. Disposed within the tubular member is an element for inhibiting the intermixing of the two fluids. A plurality of such elements, which are vaned and baffle-like, are disposed within the tubular member and arranged in end-to-end relation. The vanes of successive baffle elements project outwardly towards the interior surface of the tubular member and are curved longitudinally in opposite directions whereby the fluid flow past the baffle elements is subject to abrupt changes in directions at each successive baffle member.

Abstract: Apparatus for drawing liquids into, and expelling liquids from, a pipette including a housing comprising a hand-held pistol grip to which is connected a pipette-supporting portion. Valve means mounted on the pistol grip beneath two fingers of the user permit selective application of pressure or vacuum to one end of the pipette for drawing the liquid into, and expelling the liquid from, the pipette.