In 1923, chemists Johannes Nicolaus Brønsted and Thomas Martin Lowry independently recognized that acid–base reactions involve the transfer of a proton.
ɪn nˈaɪntiːnhˈʌndɹɪd twˈɛnti θɹˈiː, kˈɛmɪsts dʒˈoʊhænz nˈɪkəlˌaʊs bɹˈɑːnstᵻd ænd tˈɑːməs mˈɑːɹtɪn lˈoʊɹi ˌɪndᵻpˈɛndəntli ɹˈɛkəɡnˌaɪzd ðæt ˈæsɪd bˈeɪs ɹɪˈækʃənz ɪnvˈɑːlv ðə tɹˈænsfɜːɹ əvə pɹˈoʊtɑːn.