Elements used for radioactive dating
When a radioactive isotope is added in small amounts to comparatively large quantities of the stable element, it behaves exactly the same as the ordinary isotope chemically; it can, however, be traced with a Only a small fraction of the isotopes are known to be stable indefinitely.
Davy used a new method of isolating elements that he had invented, electrolysis.
(See sidebar on Davy in the calcium entry in Volume 1.) There are very few uses for potassium as a pure element.