Alexander William Williamson, Scottish chemist, c 1865.

Carte de visite photograph by H J Whitlock of Birmingham of Alexander William Williamson (1824-1904). Williamson became interested in chemistry through his medical education in Heidelberg, Germany, under Justis Liebig (1803-1873). He became Profesor of Chemistry at University College, London, in 1849. His discovery of the structure of alcohols and ethers led to the clasification of organic compounds and established the formula H2O for water.