The pressure inside the dropper is lower than atmospheric pressure, and the dropper is subjected to a downward force from the atmosphere. The solution is simple: heat the dropper with a water bath (not directly) to increase the vapor pressure inside the dropper and remove it. The frosted interface between the dropper and the dropper bottle is bonded due to chemical reactions, usually alkaline substances. At this point, acid cleaning is attempted, and if not possible, it can only be scrapped. The inner side of the drip bottle mouth is frosted, similar to a fine mouthed bottle, with the bottle cap replaced by a dropper. Containers used to hold small amounts of liquids, mostly used in laboratories