One such spring can be found here:
http://en.wikipedia.org/wiki/Lithia_Park(There's a fountain in the park that you can try- although the water's an "acquired taste" to say the least)
The discovery of its usefulness in treating for bipolar disorders, however, came quite by accident.
An Australian doctor, John Cade, along with many others, suffered terribly as a prisoner of war in the infamous Changi POW camp that the Japanese operated in Singapore. He showed great courage and compassion as a physician during this period, and some believe his POW experiences stimulated his interest in mental health.
After WWII, Dr Cade, who was also a psychiatrist, began his experiments with lithium. As with many important scientific breakthroughs, Dr Cade's discovery came about as an accident.
His original theory was that manic patients had a metabolic disorder, indicated by excessive urea in their urine. In other words, Cade was researching the historic misconception that there was some connection between mania and urea.
Cade tested his theory by injecting uric acid into guinea pigs. To do this he used lithium urate, simply because it was so highly soluble. To Cade's surprise, he found this produced a calming effect instead of increased excitation.
Through a series of very careful experiments on both guinea pigs and people, it was proven that lithium had a pronounced effect on mania.
This discovery was quickly followed by the finding that lithium also helped with the depressive symptoms of bipolar.
Cade's remarkably successful results were detailed in his paper, Lithium salts in the treatment of psychotic excitement, published in the Medical Journal of Australia (1949).
The significance of what John Cade achieved is hard to overestimate - the first effective medication to treat a mental illness! Not only that, but in the form of a cheap and natural mineral salt. Remember - this happened at a time when manic depression either went untreated, or cures were attempted through crude, early forms of lobotomies and electric shock treatment.
http://www.bipolar-lives.com/who-discovered-lithium.html