On 23 September 1885, Auer von Welsbach received a patent on his development of the gas mantle, which he called "Auerlicht", using a chemical mixture of 60% magnesium oxide, 20% lanthanum oxide and 20% yttrium oxide, which he called "Actinophor". To produce a mantle, guncotton is impregnated with a mixture of Actinophor and then heated, the cotton eventually burns away, leaving a solid (albeit fragile) ash, which glows brightly when heated. These original mantles gave off a green-tinted light and were not very successful, and his first company formed to sell them failed in 1889.