Bent Glass tube closed at one end (about 10" long) used by Marcelin Berthelot

Marcelin Berthelot used this glass tube in his synthesis of benzene from acetylene which was first carried out in 1866.

Berthelot heated the bent glass tube, containing acetylene gas, to a dull red heat and observed that the volume occupied by the gas has diminished. The major product was benzene. Berthelot also called this triacétylène since three acetylene molecules polymerise to one of benzene. Since he had previously synthesised acetylene from its elements (carbon and hydrogen) this was, in effect, the synthesis of benzene from its elements.