Vacuum pan. Coloured historical artwork of a man monitoring boiling liquid malt through an observ- ation port in a vacuum pan in a factory. He is regulating the steam and air pressures. The vacuum in the pan allows the malt extract to be thickened at a low temperature, preventing damage to its constituents. This is Allen and Hanbury's Pharmacy in Bethnal Green, London, England. Artwork from The English Illustrated Magazine (1892-93).