The Invisible Ray (1935)

Visionary scientist Janos Rukh convinces a group of scientists and supporters to mount an expedition to the African continent to locate and study an ancient meteorite of great significance. He exposes himself to the highly toxic radiation of the meteorite, and while an antidote devised by Dr. Benet saves him from death by radiation poisoning, his naked touch causes instant death to others. Back in London, the benefits of the meteorite's controlled radiation offer Dr. Benet an opportunity to restore eyesight to the blind. The antidote's toxicity excites Prof. Rukh into paranoid rages as he seeks revenge against the members of his expedition, who he accuses of stealing his discovery for their own glory.