Counting with liquids.
D002247:Carbon Isotopes; D002712:Chlorides; D006801:Humans; D007503:Iron Isotopes; D008722:Methods; D010759:Phosphorus Isotopes; D011859:Radiography / Q000295:instrumentation; D011874:Radiometry; D013325:Strontium Isotopes; D014316:Tritium
D002247:Carbon Isotopes; D002712:Chlorides; D007503:Iron Isotopes; D010759:Phosphorus Isotopes; D013325:Strontium Isotopes; D014316:Tritium