Sure thing. There’s a 1926 silent called *The Silent Storm* that had this silver‑mist effect you mentioned. The director didn’t just use a fog machine; he mixed a silver nitrate solution that would vaporise into a fine silver mist when heated, so the lead’s sorrow looked like a real storm in the frame. The trick was so delicate that the chemicals were banned after a few years, and nobody could replicate it again. Another odd one is the 1932 film *Phantom’s Shadow*. The crew rigged a camera on a treadmill and filmed the actor moving forward. They then reversed the footage to make it look like the character was floating backward through the set. The only copy of the original reels was lost in a studio fire, and that reversed‑motion trick vanished with it. So there are a few of those lost tricks, all of them disappeared because the gear or the chemicals didn’t survive the decades.