The main part of the buret is made of glass tube with uniform inner diameter and accurate scale. The lower end is connected with a glass cock or latex tube containing glass beads to control the liquid flow rate, and the bottom end is connected with a sharp glass tube. The burette with the glass cock at the lower end is called an acid burette, which is often used to measure the volume of the non strong alkaline dilute solution dripped. It is not suitable to contain alkaline solution, because the alkaline solution can corrode the glass for a long time, causing the cock to be unable to rotate.