Old and new gasometers. 19th-century artworks of an old model (left) and a new model (right) of gasometers (gas storage units) for fuels such as acetylene and wood gas. The new model has two gasification units (smaller cylinders). Gasification converts carbon-based materials, such as coal, biofuel and biomass, into a mixture of carbon monoxide and hydrogen (wood gas). These units were constructed in Paris by G. Trouve. Artworks from the first volume (1897) of 'La Revue Scientifique et Industrielle' by French chemist and inventor Jules-Louis Breton (1872-1940).