I posted this comment on the youtube video. Thanks for posting this concerto. I hope you will upload the other two movements, too, since the manuscript on IMSLP is complete. For information on Lange, see the Zentralbibliothek Zürich webpage <https://www.zbcollections.ch/home/#/content/897b0a89cd714e6c9dd6d311db380a20?tab=inhalt> that includes (under "Kontext") a brief biography as well as (under "Dateien") a detailed catalogue of his works and a photograph. Additional biographical information can be found at <http://www.archivaria.com/BusDbios/BusDbios7.html>.