His study on the Dalmatian language, Das Dalmatische (2 vol. 1906) is the only known complete description of the language, which is now extinct. He wrote it in Italian and later published a translation to German. However, the original Italian is now lost and only in 2000 an Italian translation from German was published. Bartoli used data gathered in 1897 from the last speaker of Dalmatian, Tuone Udaina, who died in 1898.
He also wrote Introduzione alla neolinguistica ("Introduction in neolinguistics", 1925) and Saggi di linguistica spaziale ("Essays of spatial linguistics", 1945) and was the teacher of Antonio Gramsci.