ˈoʊnli ˈæftɚ nˈaɪntiːnhˈʌndɹɪd fˈɪftiːn, wɪððə sədʒˈɛstʃən ænd ˈɛvɪdəns ðæt ðɪs zˈiː nˈʌmbɚ wʌz ˈɔːlsoʊ ðə nˈuːklɪɹ tʃˈɑːɹdʒ ænd ɐ fˈɪzɪkəl kˌæɹɪktɚɹˈɪstɪk ʌv ˈæɾəmz, dˈɪd ðə wˈɜːd ænd ɪts ˈɪŋɡlɪʃ ɪkwˈɪvələnt ɐtˈɑːmɪk nˈʌmbɚ kˈʌm ˌɪntʊ kˈɑːmən jˈuːs ɪn ðɪs kˈɑːntɛkst.
Only after 1915, with the suggestion and evidence that this Z number was also the nuclear charge and a physical characteristic of atoms, did the word  (and its English equivalent atomic number) come into common use in this context.