aug 1, 1774 - The element oxygen is discovered for the third (and last, so far) time – the second quantitatively, following the somewhat earlier work of Carl Wilhelm Scheele (1771–1772) by Joseph Priestley, who publishes the fact in 1775, and so names the element (and usually gets all the credit, because his work was published first)
Added to timeline:
Date:
aug 1, 1774
Now
~ 251 years ago