Insisting on a Non-negative Price: Oligopoly, Uncertainty, Welfare and Multiple Equilibria

The present invention relates to a vial which can contain metered quantities of a chemical reagent. The vial has its lower or discharge end closed by a breakable diaphragm from which there outwardly extends a flat tang housed and retained in a seat provided within a hollow element. The hollow element is mounted to a hollow body by ribs which enable it to be rotated relative to the hollow body in order to cause the diaphragm to be broken by the tang.