Dropping funnel

Note the stopcock, glass tube at the right, and ground glass joint in this pressure-equalizing dropping funnel. An ordinary dropping funnel lacks the pressure-equalizing glass tube at the right side.

A dropping funnel or addition funnel is a type of laboratory glassware used to transfer liquids. It is fitted with a stopcock which allows the flow to be controlled. Dropping funnels are useful for adding reagents slowly, i.e. drop-wise. This is desirable when the quick addition of the reagent results in side reactions, or if the reaction is too vigorous.

Dropping funnels are usually constructed with a ground glass joint at the bottom, which allows the funnel to fit snugly onto a round bottom flask. This also means it need not be clamped separately.

Dropping funnels have been in use since at least the mid-1800s.

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