The “Kaiserbrunnen” (Imperial Source) looks back on a long and storied past. It was discovered by the ancient Romans, a fact confirmed by the ancient drinking vessels and remains of a Roman bath that were found close by. Much later on, around 1700, graduation works were built to extract salt. When the healing powers of this spring were rediscovered in the middle of the 19th century, it was called "Der Sprudel" (the fountain) because it bubbled extraordinarily strongly. Its effervescence is still visible today, beneath the source's glass bonnet. The fountain was newly drilled in 1841 by order of the casino founders, Louis and François Blanc. Initial analysis was carried out by the famous German chemist, Professor Justus von Liebig, from Giessen. The name of "Kaiserbrunnen", or "Imperial Source", is also said to have been coined by him. The sodium-chloride acidulous water continues to be used as a drinking cure for heart and circulatory diseases.