Abstract: This invention provides a submersible self-priming dispenser of measured doses of toilet tank additive in which the additives are solid products which will dissolve in water. It dispenses a measured amount of the water soluble additive each time the tank is emptied. In the present invention, when the tank is full, air locks form to separate both the top and bottom openings of the dispenser from the tank and prevent the water-dissolved additive in the dispenser from mixing with the water in the tank. Dual chambered embodiments are also presented so that, if more than one additive is used, they may be kept in separate solutions between flushes.

Abstract: Each top cover of carrying and shipping containers designed for nested stacking has a first locking means for securing the cover to the container bottom. A second locking means for connecting each locked container to a similar underlying container positioned in stacked relation is located within the structure of a male component of the first locking means which is mounted in the container cover. Structures of both locking means are provided for rotary and linear sliding modes of operation. The second locking means include cam collars having upper and lower chambers, the latter housing followers which, when actuated by a finger manipulatable means accessible from the top of the containers, project and lock into the upper chambers of similar cam collars of underlying containers.