A container or vessel useful in the preparation of bacterial extracts or similar analytical samples, constructed of resilient flexible plastics material and having a releasably engageable cap (3) incorporating a nozzle (8) through which liquid contents of the container may be expressed by squeezing the container, the cap being linked to the container by a double hinge comprising two strips (14a, 14b) of material which fold back upon themselves when the container is closed by the cap, the apices (18a, 18b) of the folded hinge strips together providing contact points upon which the capped end of the container may be rested on a horizontal surface such as a work bench.