logo of University of Marburg —
Photo Credit: Own work based on: Uni Marburg Logo.svg:http://www.uni-marburg.de, CC0, https://commons.wikimedia.org/w/index.php?curid=98325161

Robert Wilhelm Bunsen —
Photo Credit: By Universitätsbibliothek Heidelberg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=66708606

Kirchhoff, Bunsen, Roscoe — Gustav Kirchhoff (left) and Robert Bunsen (center) discovered rubidium by spectroscopy. (Henry Enfield Roscoe is on the right side.)
Photo Credit: By Henry Roscoe - Public Domain, https://commons.wikimedia.org/w/index.php?curid=3534447

Rubidium —
Photo Credit:

Louis Jacques Thénard —
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=429487

Hydrogen and Oxygen react to form water —
Photo Credit: By Theislikerice, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17541441

Humboldt as a boy with his widowed mother, Maria Elisabeth (Colomb) von Humboldt —
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=31290736

Alexander von Humboldt's American expedition —
Photo Credit: By Alexrk translated by Cäsium137 (T.)