text_original: When he began his labours, chemists were not acquainted with the true com  position of a single mineral.
text_transcription: WHEN HE BEGAN HIS LABORS CHEMISTS WERE NOT ACQUAINTED WITH THE TRUE COMPOSITION OF A SINGLE MINERAL
phonemes: wˌɛn hiː bɪɡˈæn hɪz lˈeɪbɚz, kˈɛmɪsts wɜː nˌɑːt ɐkwˈeɪntᵻd wɪððə tɹˈuː kˈɑːm pəzˈɪʃən əvə sˈɪŋɡəl mˈɪnɚɹəl.