An apparatus comprising: a body including: a reaction chamber configured to include a reagent, and a solution reservoir configured to include a solution; a plunger movably coupled with the body between a starting position and a seated position, wherein: when the plunger is in the starting position, the solution reservoir is isolated from the reaction chamber, and wherein movement of the plunger from the starting position to the seated position pushes the solution into the reaction chamber; a dispensing path extending from the reaction chamber and out of the body, wherein: in a first configuration of the apparatus, the dispensing path is sealed, and in a dispensing configuration of the apparatus, the dispensing path is configured to deliver a reagent mixture formed from the solution and the reagent; a flushing means comprising a flushing chamber, different from the reaction chamber, including a flushing fluid in communication with the reaction chamber, wherein the flushing means is configured to force flushing fluid into the reaction chamber to push a specified amount of the reagent mixture through the dispensing path; characterised by a vent path extending from the reaction chamber through the flushing chamber, the vent path including open and closed configurations, wherein: in the open configuration, the vent path extends outside of the body, and the vent path vents reaction chamber gas displaced by the addition of the solution to the reaction chamber, and in the closed configuration, a portion of the vent path is sealed from the outside of the body, and flushing fluid delivered from the flushing chamber through the portion of the vent path and into the reaction chamber dispenses the reagent mixture through the dispensing path. a body including: a reaction chamber configured to include a reagent, and a solution reservoir configured to include a solution; a reaction chamber configured to include a reagent, and a solution reservoir configured to include a solution; a plunger movably coupled with the body between a starting position and a seated position, wherein: when the plunger is in the starting position, the solution reservoir is isolated from the reaction chamber, and wherein movement of the plunger from the starting position to the seated position pushes the solution into the reaction chamber; when the plunger is in the starting position, the solution reservoir is isolated from the reaction chamber, and wherein movement of the plunger from the starting position to the seated position pushes the solution into the reaction chamber; a dispensing path extending from the reaction chamber and out of the body, wherein: in a first configuration of the apparatus, the dispensing path is sealed, and in a dispensing configuration of the apparatus, the dispensing path is configured to deliver a reagent mixture formed from the solution and the reagent; in a first configuration of the apparatus, the dispensing path is sealed, and in a dispensing configuration of the apparatus, the dispensing path is configured to deliver a reagent mixture formed from the solution and the reagent; a flushing means comprising a flushing chamber, different from the reaction chamber, including a flushing fluid in communication with the reaction chamber, wherein the flushing means is configured to force flushing fluid into the reaction chamber to push a specified amount of the reagent mixture through the dispensing path; characterised by a vent path extending from the reaction chamber through the flushing chamber, the vent path including open and closed configurations, wherein: in the open configuration, the vent path extends outside of the body, and the vent path vents reaction chamber gas displaced by the addition of the solution to the reaction chamber, and in the closed configuration, a portion of the vent path is sealed from the outside of the body, and flushing fluid delivered from the flushing chamber through the portion of the vent path and into the reaction chamber dispenses the reagent mixture through the dispensing path. in the open configuration, the vent path extends outside of the body, and the vent path vents reaction chamber gas displaced by the addition of the solution to the reaction chamber, and in the closed configuration, a portion of the vent path is sealed from the outside of the body, and flushing fluid delivered from the flushing chamber through the portion of the vent path and into the reaction chamber dispenses the reagent mixture through the dispensing path.