Test tubes: performing varying tasks

Also known as culture tube or sample tubes, test tubes are the common piece of laboratory glassware. Consisting of finger-like length of glass the test tubes are open at the top end and have the rounded U-shape. Also some test tubes with larger sizes are specifically designed for boiling the liquids and are known as boiling tubes. Like other glassware the test tubes are transparent and the colors of chemicals and other elements inside can be clearly visible from outside.

In scientific laboratories, the test tubes are used for holding, mixing or heating the small quantities of liquid or solid chemicals. Usually the test tubes are used in qualitative experiments and assays. The rounded U-shaped bottom and the straight sides of the test tunes reduce or minimize the   mass loss of liquids or solid while pouring. Also pouring becomes easier due to its particular structure. Sometimes the test tubes are used to capture gases as in electrolysis demonstrations. In the biology laboratories, the test tubes are used for handling the living organisms like molds, bacteria, seedlings and plant cuttings etc. The test tubes with stoppers are used to store the chemicals and biological samples temporarily.

Like all other glassware, the test tubes need to have certain features. The test tubes need to be heated and therefore it is necessary that they are resistant towards thermal shocks. Again, the test tubes have to deal with chemicals more than any other scientific glassware in the laboratory and hence they need to be chemical resistant. Like many other glassware, the test tubes are usually made of borosilicate glass.

Buchner Funnel: making filtration easier

Named after the industrial chemist Ernst Buchner, a Buchner funnel is a piece of laboratory equipment that is used for filtration or separation of liquid from solid. Traditionally the Buchner funnel was made out of porcelain but now the funnels made of glass materials have become quite common. The vacuum sucks the air out of the Buchner flask and when the mixture of solid and liquid is poured into the container, the liquid is sucked through the sintered disc whereas the solid fails to pass through the filter disc. Usually the Buchner funnel is used in the organic chemistry experiments where the unwanted solid needs to be removed from the liquid.

One of the best advantages of using Buchner funnel is that due to the suction, the re-crystallized material gets dried automatically and you do not need to dry it separately. Buchner funnel is often used as a combination of Buchner ring, sinter seals and Buchner flask. The seal needs to be vacuum tight else there occurs problems in suction.

Though the task preformed by the Buchner funnel looks quite simple yet there is no other device in the laboratory that can replace the role of Buchner funnel. Usually the set of Buchner funnel comes in a kit and you need to set it up in the laboratory. But setting up of Buchner funnel is not at all difficult. Even if you have little experience with it, you can do it without anyone’s guidance and support.