The other major innovation was a chemical one. In Daguerre's original process, the plate was sensitized by exposure to iodine fumes alone. A breakthrough came with the discovery that when exposure to bromine or chlorine fumes was correctly combined with this, the sensitivity of the plate could be greatly increased, which in turn greatly reduced the required exposure time to between fifteen and thirty seconds in favorable lighting conditions, according to Eder. Several experimenters discovered the propensity of using chlorine and bromine in addition to iodine: Wolcott, whose "Wolcott's mixture" was marketed by his partner, John Johnson that they called "quickstuff"; two unrelated individuals with the surname Goddard – Philadelphia physician and chemist Paul Beck Goddard, and John Frederick Goddard who lectured at the Adelaide Gallery before assisting Beard with setting up the first daguerreotype portraiture studio on the roof of the Regent Street Polytechnic; (John Frederick Goddard was the first to publish information that bromine increased the sensitivity of daguerreotype plates in the "Literary Gazette" of 12 December 1840) and in Vienna: Krachowila and the Natterer brothers.