A dropping funnel is equipment which is widely used in labs for number of experiments. It is laboratory glassware that is used to transfer liquid solvent or solution. The stopcock is fitted on its one of the end; which allows the flow to be controlled. To add reagents we mostly use dropping Funnels, as it drops particular fluid slowly, i.e. drop-wise. This may be desirable when the quick addition of the reagent may result in side reactions, or if the reaction is too vigorous. Round glass Joint is usually fitted with this funnel and it allows the funnel to fit snugly onto. This also means it need not be clamped separately.
Dropping funnels have an additional narrow-bore glass tube from the bulb of the funnel, to the ground glass joint around the stem. These replace the liquid volume lost in the bulb with the equivalent gas volume from the flask into which the reagent is flowing, and are useful when handling air-sensitive reagents in a sealed, inert-gas environment. Without this tube, or some other means to equalize the pressure between a sealed receiving flask and the bulb of the funnel, the flow of fluid from the bulb will rapidly come to a halt.
