An Erlenmeyer flask, commonly known as a conical flask or E-flask, is a widely used type of laboratory flask which features a flat base, a conical body, and a cylindrical neck. The flask is named after the German chemist Emil Erlenmeyer, who created it in 1861.
The Erlenmeyer flask is usually marked on the side (graduated) to indicate the approximate volume of their contents, and has a spot of ground glass or rough white enamel where it can be labeled with a pencil. It differs from the beaker by its tapered body and narrow neck.
The opening usually has a slight rounded lip so that the flask can be easily stoppered using rubber bungs or cotton wool. Alternatively, the neck may be fitted with a female ground glass joint to accept a glass stopper. The conical shape allows the contents to be swirled or stirred during an experiment, either by hand or by a shaker or magnetic stirrer; the narrow neck keeps the contents from spilling. The smaller neck also slows evaporative loss better than a beaker. The flat bottom of the conical flask makes it unlikely to tip over, unlike the Florence flask.
Erlenmeyer flasks are used in chemistry labs for titration, especially of pH.
Erlenmeyer flasks are often used to heat liquids, e.g. with a Bunsen burner. For that purpose, the flask is usually placed on a ring held to a ring stand by means of a ring clamp. A wire gauze mesh or pad is usually placed between the ring and the flask to prevent the flames from directly touching the glass. An alternative way to set up the apparatus is to hold the flask by the neck with a test tube clamp fixed to the stand.
If the flask is to be heated in an oil or water bath, a 'C' shaped lead or iron weight may be placed over the conical part of the flask to prevent it from floating in the bath.
Erlenmeyers are also used microbiology for the preparation of microbial cultures. Plastic Erlenmeyer flasks used in cell culture are pre-sterilized and feature closures and vented closures to enhance gas exchange during incubation and shaking. (Wikipedia)