vˈaɪɾəl hˈiːt wʌzɐ sˈʌmwʌt kˌɑːntɹəvˈɜːʃəl sˈʌbdʒɛkt bɪkˈʌz ɪt wʌz fˈɔːɹmɚli bᵻlˈiːvd ðæt hˈiːt wʌz ɐkwˈaɪɚd baɪ ɐn aʊtsˈaɪd sˈoːɹs sˈʌtʃ ɐz ðɪ ˈɛlɪmənt ʌv fˈaɪɚ.
Vital heat was a somewhat controversial subject because it was formerly believed that heat was acquired by an outside source such as the element of fire.