This one is a day late, but trust the Siren. You will read nothing (at least, nothing non-political) in the coming week that will make your blood run any colder than the following anecdote. Have a strong drink ready. This is from Kate Buford's fine biography Burt Lancaster: An American Life. It is 1959, and Lancaster is shooting Elmer Gantry with director Richard Brooks.
Six days were budgeted for shooting the spectacular fire climax scene...The exteriors were shot at the back of a skating rink at the end of an old Santa Monica pier, but six days were not nearly enough for what Brooks claimed was Hollywood's first 'mass interior fire scene.' Lancaster got UA to allow him and Brooks to take the extra $200,000 needed from their fees and the scene was then shot in about five weeks using highly flammable old nitrate films from the Columbia vault to spread the conflagration.
Update: From Yojimboen, in comments:
Let me reassure all concerned, the nitrate film used by Brooks was old print material, badly-deteriorated and slated to be destroyed anyway. I’m old enough to have attended a Q & A session with Brooks at the London Film School in March 1964 at which -- after screening Elmer Gantry with the students -- he spoke in great detail of the fire sequence. Technicians laid single strips of 35mm nitrate print across beams, draped in bunting, etc. Brooks explained they experimented with accelerants but none spread flames at the desired speed. He thought of using nitrate film. He emphasized he was hyper-cautious about safety – the low-angle shots of the flames racing across beams and bunting were filmed mostly without actors present. He also stressed, repeat stressed, that he and Lancaster made sure the old nitrate prints were backed up by other prints and negatives. Brooks was nothing if not a movie lover, with a healthy consciousness of cinema history.
Yojimboen is a new commenter (and most welcome!) but the Siren certainly hopes he (or she) is correct. Many thanks for the additional information. The Siren isn't kidding when she says she'll sleep better tonight. Also check out Karen's comment, concerning the AFI documents about Gantry's censorship troubles. (Buford goes into those too.)
The Siren is continually amazed at the depth and breadth of knowledge of the people who are kind enough to stop by her corner of the Internet.