Bottle Weighing

U–tube filled with a sodium hydroxide is used for a cleaned and dried gas. U–tube filled with a 1 mol dm^–3 aqueous potassium nitrate solution is used as a permanent salt bridge. U–tube is a device used for water electrolysis, for laboratory hydrogen and oxygen obtaining.

Density bottles are mainly used to determine the density of liquids of moderate viscosity. They are not volumetric instruments, however, they are calibrated ‘to contain ‘ as in the case of volumetric flasks.