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.
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.