with wool, glasswool or a bung/cork which has a small bore made in it) and the drying tube is connected to the apparatus to be kept dry via the ground glass joint. If the drying tube is bent the bend is oriented so that solid desiccant does not fall into the reaction vessel. Some drying tubes have a glass sinter to prevent desiccant falling into the reaction vessel.
The apparatus uses wool, glasswool, or a bung/cork with a small hole to keep the reaction vessel dry. A connecting tube is used and secured via a ground glass joint. If the tube is bent, it's designed so that desiccant doesn't fall into the reaction vessel. Some tubes have a sintered glass component to prevent this from happening.