I just asked my wife (she's a chemistry teacher) when the pH scale was invented and she said she wasn't sure (yay - brownie points for me and wikipedia for knowing something she didn't...). Turns out the answer is 1909:RetroTechGuy wrote:"Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14"
Gosh, they had precision pH measurements in 1751? Interesting..
http://www.carlsberggroup.com/Company/h ... Value.aspx
Key word is estimated I guess. Still, testing of sediments etc would probably offer some good clues if properly interpreted.