Libby and his team intially tested the radiocarbon method on samples from prehistoric Egypt.
They chose samples whose age could be independently determined.
14C also enters the Earth's oceans in an atmospheric exchange and as dissolved carbonate (the entire 14C inventory is termed the carbon exchange reservoir (Aitken, 1990)).
Thus, one carbon 14 atom exists in nature for every 1,000,000,000,000 C12 atoms in living material.The 14C formed is rapidly oxidised to 14CO2 and enters the earth's plant and animal lifeways through photosynthesis and the food chain.The rapidity of the dispersal of C14 into the atmosphere has been demonstrated by measurements of radioactive carbon produced from thermonuclear bomb testing.A sample of acacia wood from the tomb of the pharoah Zoser (or Djoser; 3rd Dynasty, ca. Libby reasoned that since the half-life of C years, they should obtain a C14 concentration of about 50% that which was found in living wood (see Libby, 1949 for further details).The results they obtained indicated this was the case.