For security reasons, the Army had Kellogg establish a wholly owned subsidiary, the Kellex Corporation, so the gaseous diffusion project could be kept separate from other company work. "Kell" stood for "Kellogg" and "X" for secret. Kellex operated as a self-contained and autonomous entity. Percival C. Keith, Kellogg's vice president of engineering, was placed in charge of Kellex. He drew extensively on Kellogg to staff the new company, but also had to recruit staff from outside as well. Eventually, Kellex would have over 3,700 employees.