A dispensing device (10) for dispensing a measured amount of a chemical (60) into a fluid piping system including a cap member (24) having a fluid inlet port (33) and a fluid outlet port (34) between which is a tubular flow conduit (28). The cap member (24) also includes bypass and control members (44), which align with an inlet passageway (36) and an outlet passageway (42) in the cap member (24). Fluid flows into the cap member (24) through the inlet port (33). The tubular flow conduit (28) has the inlet passageway (36) therein to divert a portion of the fluid passing through the system into a canister (11) operatively connected to the cap (24). A container (16) is disposed within the canister (11) containing the chemical (60), which is partially dissolved by fluid introduced into the container (16) to create a use solution. The use solution passes out of the canister (11) through the outlet passageway (42) in the tubular flow conduit (28) located downstream from the inlet passageway (36) and is reintroduced into the fluid system to flow out of the outlet port (34). The bypass and control members (44) may be used in variable positions to control and meter the amount of use solution being dispensed.