Abstract: A method and apparatus for simultaneous optical measurement of several characteristics of each particle of a group of small particles while the particles are suspended in a liquid. The apparatus includes a sample passage structure through which the particles pass, and a first optical detector structure which receives light from the sample passage structure. The sample passage structure and detector are aligned one with respect to the other. The output of a source of light is directed to the sample passage structure by an alignment device which aligns the light and the sample passage structure. A second optical detector receives the light passed by the sample passage structure.

Abstract: Liquid sampling apparatus including a sampling head incorporating a floating pressure seal effected by a positive pressure introduced into an open top sample container in which the sampling head is telescopically introduced. The liquid sampling apparatus includes a compartment having at least an entrance, a cover slidable within said compartment and the sliding cover carrying the sampling head. The sliding cover has a depending shield capable of closing off the entrance to the compartment when the assembly head is therein introduced.The floating pressure seal is defined by a mounting ring seated in a suitable passageway formed in the cover. The mounting ring has a central aperture and a plunger is slidable within said aperture, one end of the plunger being threaded and having an adjusting ring threadably engaged thereupon for limiting the extent of free movement of the plunger relative to the mounting ring. The other end of the plunger has an enlarged head or piston.