The basic buret is used to hold alkaline solution. Its lower end is connected with a rubber tube. Glass beads are placed in the rubber tube to control the flow of solution. A pointed glass tube is connected to the lower end of the rubber tube. Any solution that can react with the rubber tube, such as potassium permanganate, iodine and other solutions, cannot be put into the basic buret.

The calibration of the buret is the same as that of the volumetric flask. The water weighing method is used, that is, according to the different densities of pure water at different temperatures, the water quality at different scales of the buret is measured according to V=m/ ρ， Calculate the volume of pure water at a new temperature, which is the real volume of the buret at the new scale.