Carlson's early experiments, conducted in his apartment kitchen, were smoky, smelly, and occasionally explosive. In one set of experiments, he was melting pure crystalline sulfur (a photoconductor) onto a plate of zinc by moving it just so over the flame of his kitchen stove. This often resulted in a sulfur fire, filling the building with the smell of rotten eggs. In another experiment, the chemicals he was working with caught fire, and he and his wife were hard-pressed to extinguish the flames.