Abstract: A mixing and dispensing apparatus for mutually reactive chemicals. The apparatus includes a mixing chamber having a core of inexpensive monolithic design with a reciprocal. The core and purging rod are readily detachable as a unit from the remainder of the apparatus. The purging rod does not perform a valving function, and therefore significant compressive force does not need to be maintained on the mixing chamber core. The apparatus includes separate valves for each of the reactive components remote from the mixing chamber bore which are automatically opened after retraction of the purging rod, so that the chemicals are not maintained under pressure adjacent the purging rod. A visible indication of the amount of useful life remaining for the mixing chamber is also provided.