Abstract: Disclosed is a valve assembly having a housing defining a flow passage with an inlet port and a shoulder surrounding the port. The shoulder is chamfered in an upstream direction. A valve seat formed of a gold material, preferably 24 karet gold, is disposed on the shoulder. The margin of the seat about its central opening is deformed in an upstream direction against the chamfer. A sapphire ball seats against the deformed seat to seal the flow passage through the valve assembly.

Abstract: An absorbance measuring photometer, for measuring the absorbance of a sample in a sample cell, in which light of preselected wavelengths from one of two alternately utilizable sources of different wavelengths is formed into a beam and the etendu of the beam defined. The beam is then split into two separate beams one of which is directed through the sample cell onto a first detector and the other of which is passed directly onto a reference detector. The beam is so directed though the sample cell that it does not touch the cell walls and both beams are imaged on their respective detectors so as to be wholly within the photosensitive area thereof.

Abstract: A diluter for use in a kinetic analysis apparatus for picking up a serum sample from a container and diluting it into a reaction cup in which a diluter probe mounted for vertical translation and horizontal rotational motion is coupled to a sample pump with the sample pump coupled to a diluter pump and wherein the probe is caused to be lowered into a container of serum sample after which said sample pump draws into said probe a measured amount of sample whereupon said probe is raised, rotated and then lowered to a position over a reaction cup; the diluter pump is then operated to discharge said sample along with a measured amount of diluent. Vertical translation and horizontal rotation of the probe is achieved by means of a pair of coaxially disposed cylindrical cam members one of which is fixed and the other rotatable about the common axis.