Bunsen and Kirchhoff

The successes of the past are haunting us; Trinity College will never get out of the shadow of Newton, for Göttingen this shadow is cast by Gauss and Riemann, and for Heidelberg it is Bunsen and Kirchhoff. Bunsen's statue stands high in the Hauptrasse of the Heidelberg Altstadt, in front of the house where he discovered spectroscopy.

(A lesser known fact: Bunsen collaborated with Mendeleev in Heidelberg,  who lived near the Uni Platz:  no commemorative tablet is in place there, which is a great shame).

One of Bunsen's contributions is the confirmation of six elements in the atmosphere of the Sun (despite Comte's comment on the impossibility of the task), and later discovered two new elements spectroscopically: Rubidium and Caesium, obtained from the Bad Dürkheim springs. Quite insane amounts were required  for establishing the discovery  (40 tonnes), and the proper isolation required mineral samples from various mines, e.g., in Moravia. The original samples themselves can be seen in the Neuenheimer Feld chemistry building.

The Dürkheim springs were known for the high arsenic content. We took a little sip from a nearby spring, but spit it out anyway as it was as salty as sea water.