Another improvement that followed along the lines adopted by Edison for the commercial development of the phonograph was making the recording and reproducing styluses of sapphire, an extremely hard, non-oxidizable jewel, so that those tiny instruments would always retain their true form and effectively resist wear.
"Edison, His Life and Inventions"
Frank Lewis Dyer and Thomas Commerford Martin
That the process was wholly an oxidising one, the work being done entirely by the oxygen set free from the hypochlorous acids in the presence of oxidizable matter....
"Chlorination of Water"
Joseph Race
The luciferins, as the oxidizable substances, must claim first attention.
"The Nature of Animal Light"
E. Newton Harvey