A very common instrument in most school and research laboratories, the Bunsen gas burner was first used by Robert Bunsen and Gustav Kirchhoff in their experiments with spectroscopy, a means of analyzing the elemental constituents of chemicals. Because of its ability to create a very hot and nearly invisible flame, the Bunsen burner was ideal for heating elements to incandescence; samples could be heated until they glowed, allowing Bunsen and Kirchhoff to observe the characteristic spectral pattern emitted by the element. Actually a modification of a device used by Michael Faraday, the Bunsen burner is essentially a metal tube into which a gas line is fed. At the base of the tube is a series of openings that allow air into the system. Because air is added prior to burning, the flame produces very little light and smoke. The height and heat of the flame are very easy to control, making it a useful tool for student scientists. Torches using a design similar to Bunsen's are often used for soldering.