In 1875 Swan returned to consider the problem of the light bulb with the aid of a better vacuum and a carbonized thread as a filament. The most significant feature of Swan's improved lamp was that there was little residual oxygen in the vacuum tube to ignite the filament, thus allowing the filament to glow almost white-hot without catching fire. However, his filament had low resistance, thus needing heavy copper wires to supply it. Swan first publicly demonstrated his incandescent carbon lamp at a lecture for the Newcastle upon Tyne Chemical Society on 18 December 1878. However after burning with a bright light for some minutes in his laboratory, the lamp broke down due to excessive current. On 17 January 1879 this lecture was successfully repeated with the lamp shown in actual operation; Swan had solved the problem of incandescent electric lighting by means of a vacuum lamp. On 3 February 1879 he publicly demonstrated a working lamp to an audience of over seven hundred people in the lecture theatre of the Literary and Philosophical Society of Newcastle upon Tyne, Sir William Armstrong presiding. Swan turned his attention to producing a better carbon filament and the means of attaching its ends. He devised a method of treating cotton to produce 'parchmentised thread' and obtained British Patent 4933 on 27 November 1880. From that time he began installing light bulbs in homes and landmarks in England. His house, Underhill on Kells Lane in Low Fell, Gateshead, was the world's first to have working light bulbs installed. The Lit & Phil Library in Westgate Road, Newcastle, was the first public room lit by electric light during a lecture by Swan on 20 October 1880. In 1881 he founded his own company, The Swan Electric Light Company, and started commercial production.