Priestly

It was the British philosopher-scientist Joseph Priestly who discovered how to create seltzer water by dropping sulfuric acid onto chalk and encouraging the resulting carbon dioxide gas to dissolve into an agitated bowl of water. He speculated that drinking the water might ward off scurvy on Captain James Cook's voyage to the South Seas (he was wrong). Priestly continued experiments with gasses, and his Experiments and Observations on Different Kinds of Air led to the discovery of photosynthesis. Priestly himself, in the course of his experiments discovered Oxygen (O2), and even predicted so-called "Oxygen Bars," where customers inhale the stuff in its pure form: "The feeling of it to my lungs was not sensibly different from that of common air; but I fancied that my breast felt peculiarly light and easy for some time afterwards. Who can tell but that, in time, this pure air may become a fashionable article in luxury."
Priestly's philosophical writings, especially those detailing his committed materialism (though not atheism), his Unitarianism, and his strong support of the French Revolution in a country where it was anathema led to his forced emigration to Pennsylvania, where his theological friends Benjamin Franklin and Thomas Jefferson welcomed him. Upon his death in 1804, French scientist George Cuvier called him "the Father of Modern Chemistry".