ɪn wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd ˈeɪɾi fˈoːɹ, svˈænt ɚrhˈiːnɪəs ɐtɹˈɪbjuːɾᵻd ðə pɹˈɑːpɚɾiz ʌv æsˈɪdᵻɾi tə hˈaɪdɹədʒən ˈaɪɑːnz ˈeɪtʃ plˈʌs, lˈeɪɾɚ dᵻskɹˈaɪbd æz pɹˈoʊtɑːnz ɔːɹ hˈaɪdɹənz.
In 1884, Svante Arrhenius attributed the properties of acidity to hydrogen ions (H+), later described as protons or hydrons.