Dissolution test vessel with integral verticality control

A dissolution test apparatus comprising:

• a vessel support member comprising a top surface and an inside edge circumscribing an aperture;
• and
• a vessel extending through the aperture and comprising:
• a cylindrical section coaxially disposed about a central axis of the vessel, the cylindrical section comprising an inside vessel surface, an outside vessel surface opposing the inside vessel surface, an upper end region circumscribing a vessel opening, and a lower end region axially spaced from the upper end region;
• a bottom section disposed at the lower end region;
• and
• a flange coaxially disposed about the central axis, the flange comprising a main flange portion extending radially outward from the outside vessel surface at the upper end region, and a bottom surface facing generally toward the lower end region and perpendicular to the inside vessel surface, wherein the bottom surface lies in a horizontal plane and is entirely coplanar with the horizontal plane,
• wherein the inside vessel surface is parallel to the inside edge of the vessel support member.