Task: Question Answering
Input (English): Passage: In 1880, Bell received the Volta Prize with a purse of 50,000 francs (approximately US$250,000 in today's dollars) for the invention of the telephone from the Académie française, representing the French government. Among the luminaries who judged were Victor Hugo and Alexandre Dumas. The Volta Prize was conceived by Napoleon Bonaparte in 1801, and named in honor of Alessandro Volta, with Bell receiving the third grand prize in its history. Since Bell was becoming increasingly affluent, he used his prize money to create endowment funds (the 'Volta Fund') and institutions in and around the United States capital of Washington, D.C.. These included the prestigious 'Volta Laboratory Association' (1880), also known as the Volta Laboratory and as the 'Alexander Graham Bell Laboratory', and which eventually led to the Volta Bureau (1887) as a center for studies on deafness which is still in operation in Georgetown, Washington, D.C. The Volta Laboratory became an experimental facility devoted to scientific discovery, and the very next year it improved Edison's phonograph by substituting wax for tinfoil as the recording medium and incising the recording rather than indenting it, key upgrades that Edison himself later adopted. The laboratory was also the site where he and his associate invented his "proudest achievement", "the photophone", the "optical telephone" which presaged fibre optical telecommunications, while the Volta Bureau would later evolve into the Alexander Graham Bell Association for the Deaf and Hard of Hearing (the AG Bell), a leading center for the research and pedagogy of deafness. Question: The Volta lab improved the phonograph by replacing tinfoil with what substance?
Output (English): wax