If garden seeds float or sink to show if seed is stil viable?

CAn you tell whether old garden seeds will still germinate, based on whether they float or sink in a glass of water?

If garden seeds float or sink to show if seed is stil viable?
That's really not reliable... some seed types float naturally; others sink naturally. It doesn't really say whether they're viable or not.
Reply:let them soak for at least 36 hours and if they are still floating they are dead