burette
/ byoo-RET /
Picture a tall, slim measuring tube standing upright, with a tap at the bottom you can ease open just enough to release one drop at a time. That careful dripping tube is a burette, the chemist's tool for adding liquid slowly and reading off precisely how much went in.
A burette is a long graduated glass tube, narrow and marked in fine divisions, with a stopcock at the lower end. You fill it with titrant, note the starting reading, release liquid drop by drop into the sample, and note the final reading; the difference is the delivered volume.
It matters because the burette is the heart of a titration's accuracy — it lets you control delivery to a fraction of a drop and read volume to about a hundredth of a millilitre. Reading it well takes care: you sight the bottom of the curved liquid surface at eye level to avoid a parallax mistake.
An analyst fills a 50 mL burette with standard base, records 0.05 mL at the start and 23.40 mL at the end point; the titrant delivered is 23.35 mL.
Final reading minus initial reading equals the delivered volume.
A burette delivers a variable volume that you read off each time, unlike a volumetric pipette or flask, which is built to hold one fixed volume. Always read at the bottom of the meniscus with your eye level to it.