Long ago when I was in university, I took an English writing course that had us read all kinds of essays and then write about them. I have a memory of one essay that was about early photographers and how many of them died because they did not realize how deadly potassium (or sodium) cyanide was. For a reason unknown to me, cyanide was part of the development process then. I am not sure what time frame this essay was dealing with. Anyway, the photographers would bit the cyanide pellets to break them into smaller pieces and then of course, die due to ingestion. I really wish I still had that essay! Was this true? Was cyanide used as a photographic developing chemical? If yes, when was its use discontinued?