He mentions deuterium, Harold Urey's experiments, and the fact a quart of the substance would be worth $100,000, but I'm sure 99% of the 1935 audience didn't know what he was talking about anyway. I disliked this development, sensing it was just a plot device to keep the movie rolling, and I was right. That idea was pulled out of thin air in an effort to explain why people drinking water would be poisoned. The murder mystery gets off to a good start, but then falters when Vance speculates that perhaps it was 'heavy water' that was used as the poison, since it was not known if that substance was poisonous. As good an actor as Paul Lukas is, his accent destroys the illusion that he's the great American detective, Philo Vance, and I was conscious of that throughout.
