Science: Three-Ton Question

The scene: Westinghouse Electric’s quiet little uranium laboratory. The time: early 1942, when the world’s total uranium metal supply was measured in grams and ounces. The action began with an urgent telephoned question from Dr. Arthur H. Compton’s mysterious Metallurgical Laboratory in Chicago: “How soon can you supply three tons of pure uranium?” Westinghouse’s practical answer is a drama that has just been made public.

Two Westinghouse research scientists, in the process of making, testing and rejecting uranium for lamp filaments, had developed an efficient method for extracting and refining uranium. Their metal was the purest available, and an occasional dribble of thumb-size pellets filled the modest requirements of college and research laboratories. Then the telephone call came. Dr. Harvey C. Rentschler and Dr. John W. Harden were not dismayed.

Washtubs & Sun Lamps. The three-ton question allowed no time for designing or building machinery. Dr. Harden used his laboratory as a factory and tried every short cut he could think of. First step was pouring a solution of uranium salt and other chemicals into a battery of wooden washtubs on the roof. There the photochemical action of the ultraviolet rays in sunlight (on cloudy days, sun lamps) converted the transparent liquid into green, powdery potassium uranium fluoride. The second step: melting this secondary uranium salt in graphite cups for electrolytic separation of the pure metal. The electrodes were raised and lowered by automobile jacks. The final step was simple melting and casting.

Within a few months, daily uranium output was stepped up from eight ounces to more than 500 lbs., and the cost dropped from $1,000 a lb. to $22. By 1943, bigger & better production methods were ready to take over, and Drs. Rentschler & Harden were able to quit their little makeshift. But in the emergency, they had supplied more than the asked-for three tons of pure uranium, for the first atomic pile.